S3 GT-I9300 not bootable, stuck on Samsung logo and not chargin - Galaxy S III Q&A, Help & Troubleshooting

Hello community, I need your help.
I have a Samsung S3 GT-I9300 (not rooted) and the problems began with a sometimes flickering display at approximately ~60% accumulator loading state.
The phone went off. After that the S3 could be switched on and worked ok.
Over 2 months the intervals for that behaviour became shorter and were more frequent.
Then on one day a message appeared such as that a new OS will be installed although NO new OS was downloaded!
I misinterpreted the situ, carried out NO backup and the following was that the S3 is now stuck on the samsung logo.
After removing the accumulator this ended and after reinserting the samsung logo appeared again.
The next behaviour was I connected the S3 via USB cable to load the accumulator then suddenly the accumulator symbol stayed gray and freezed.
I tried to reconnect, nothing changed. (I loaded the accumulator with the S3 of my friend and it worked)
Also now I cannot connect via USB with a PC, which worked always before the "crash".
Then I tried to enter the recovery mode.
The displayed message was:
Android system recovery (3e)
Volume up/down to move highlight;
power button to select.
reboot system now
apply update from ADB
apply update from external storage
wipe data/factory reset
wipe cache partition
apply update from cache
---------------------------------------------------------------
E:failed to mount /system (Invalid argument)
# MANUAL MODE #
-- Appling Multi-CSC...
E:failed to mount /system (Invalid argument)
can't mount '/system' (Invalid argument)
E:failed to mount /system (Invalid argument)
Click to expand...
Click to collapse
Obviously the S3 is no more bootable. Probably caused by a hardware defect...
My next idea was to install a file manager to save the datafiles (contacts, whatsapp chats, viber chats, telegram chats, etc.)
I found an information about the AROMA-Filemanager (e.g. aromafm-1.91.zip) which is stated to work by booting from the external SD-card.
The displayed message was then:
-- Install / sdcard ...
Finding update package...
Opening update package...
Verifiying update package...
E:signature verification failed
E:failed to mount /system (Invalid argument)
-- Appling Multi-CSC...
E:failed to mount /system (Invalid argument)
can't mount '/system' (Invalid argument)
Installation aborted.
Click to expand...
Click to collapse
So now I'm really helpless, what to do to get access to the datafiles...
The outlined facts:
1. there ist no working booting system on the S3
2. the usb port is not working
3. AROMA-Filemanager on SD card does not work
The essential question for me is compared to PC's: is it possible to get successfully access to the system such as 'knoppix software' for pc partitions?
What is the meaning of -- Appling Multi-CSC... ??
Is there a chance to flash e. g. an OI File Manager??

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Try to flash the stock ROM using Kies.
Open Kies and select the option similar to 'Initilize' from the menu bar.
You need to plug the phone to the PC via USB cable after booting into the download mode.
Before that, make a note of the S/N of your phone which is at the back of the phone. Will be visible after removing the battery.
Kies will ask for this S/N so after entering the S/N the process starts.
Check if this works. But your old data in your internal storage will be lost.

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....there is no working USB connection!!!
mpadhu said:
Try to flash the stock ROM using Kies.
Open Kies and select the option similar to 'Initilize' from the menu bar.
You need to plug the phone to the PC via USB cable after booting into the download mode.
Before that, make a note of the S/N of your phone which is at the back of the phone. Will be visible after removing the battery.
Kies will ask for this S/N so after entering the S/N the process starts.
Check if this works. But your old data in your internal storage will be lost.
Click to expand...
Click to collapse
as already stated in my opening:
...
Also now I cannot connect via USB with a PC, which worked always before the "crash".
...
Click to expand...
Click to collapse
===> Sorry to say that,
your tip is useless!

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actually I kept on trying to clarify if it is really not possible to connect the S3 via USB with a PC.
Approximately after a minute S3 connected via USB with the PC the connect sound appeared and after a second appeared again. . .
. . . so I connected and disconnected. . . and on and on . . .
Then after more tries the connect sound appeared and in the Windows devicemanager the 2 entries popped up!
. . .
- Portable Devices
- GT-I9300
.
.
- USB-Controller
- SAMSUNG Mobile USB Composite Device
But in ADB
with the adb command
adb usb
the result was
error: device not found
so no connection could be established. . .
Has anyone proposals???

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stuck on samsung logo
im using s3 i9300. i ****ed up my phone ...
if i upgrade using kies than network dont work
if i install any other rom it goes into insane bootloop.
than i try different things...now i cant open my recovery even through...its stuck on samsung logo
what should i do??
>>need some hep<<

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@Maclane: does the phone reach downloadmode, by Vol-Power Home?

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downloadmode is accessible
rp158 said:
@Maclane: does the phone reach downloadmode, by Vol-Power Home?
Click to expand...
Click to collapse
@ rp158
Yes, the downloadmode is easily accessible by buttons . . .

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@Maclane: ...and you've for moments USB-connection PC-phone. So try the usual things:
1. Use the USB-port of the motherboard of PC.
2. Deinstall Odin and all Samsung-drivers.
3. Goto sammobile.com (not the mobile version), choose your phone & country and find your actual firmware, matching Odin-version and drivers. Download & install them and try to connect again between Odin & phone.
4. Flash the firmware. Good luck.

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rp158 said:
@Maclane: ...and you've for moments USB-connection PC-phone.
Click to expand...
Click to collapse
as mentioned already above: No, I cannot establish a working connection between S3 and PC to work with !
with regard to install new firmware I can only use the SDcard!
with regard to the procedure: Now that is not the question! ==> as already stated in my opening: my focus is to save the old datas.
if I flash new firmware, all is lost!
kind regards

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use of launcher for oi file manager
Hello community,
what about the following concept:
To save the old datas, is it possible to install a launcher on the SD card e. g. for working with the oi file manager on the smartphone / SD card without damaging / deleting the old datas?
How this could be realised?
Does this make sense?
kind regards