one m8 stuck with exclamation marks in each corner - AT&T HTC One (M8)

I was trying to restore my friend's gpe back to sense because they were having a lot of problems with the gpe install.
No matter what I do it willo boot to the htc screen with exclamation marks in each corner and if i unplug the phone from the pc i get a white bootloader screen it says software status: official
***unlocked***
m8_ul_ca pvt ship s-off
cid-bs_us002
some other stuff
RUU (in orange) last line
a paste of fastboot getvar all:
C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot getvar all
< waiting for device >
(bootloader) version: 0.5
(bootloader) version-bootloader: 3.19.0.0000
(bootloader) version-baseband: 1.29.214500021.24_2G
(bootloader) version-cpld: None
(bootloader) version-microp: None
(bootloader) version-main: 1.54.401.5
(bootloader) version-misc: PVT SHIP S-OFF
(bootloader) serialno: HT49VWM05000
(bootloader) imei:
(bootloader) imei2: Not Support
(bootloader) meid: 00000000000000
(bootloader) product: m8_ul_ca
(bootloader) platform: hTCBmsm8974
(bootloader) modelid: 0P6B12000
(bootloader) cidnum: BS_US002
(bootloader) battery-status: good
(bootloader) battery-voltage: 0mV
(bootloader) partition-layout: Generic
(bootloader) security: off
(bootloader) build-mode: SHIP
(bootloader) boot-mode: RUU
(bootloader) commitno-bootloader: 76df2b54
(bootloader) hbootpreupdate: 11
(bootloader) gencheckpt: 0
all: Done!
finished. total time: 0.074s
Can someone walk me through restoring this phone please?!? I'd be greatly appreciative.
fastboot commands still work with the phone but I don't know what to do
thank you all for your help

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ayocam said:
No matter what I do it willo boot to the htc screen with exclamation marks in each corner
Click to expand...
Click to collapse
This statement doesn't actually tell us anything about what you tried (or didn't try), which is critical in us helping you.
Please list in detail, the steps you've tried so far, including exact names of files used, specific results (including any error messages and status of the phone after each "attempt").
ayocam said:
(bootloader) version-bootloader: 3.19.0.0000
(bootloader) version-baseband: 1.29.214500021.24_2G
(bootloader) version-main: 1.54.401.5
(bootloader) modelid: 0P6B12000
(bootloader) cidnum: BS_US002
Click to expand...
Click to collapse
The above info indicates a mish-mosh of various mods, either before you got a hold of the phone, or a result of the steps you took (or a combination of those two);
- If this was originally the AT&T variant, it was changed to Dev Edition CID
- Not sure, but I think that is the Dev Edition Marshmallow (MM) radio baseband number (or at least some other version MM radio), so apparently had that firmware flashed?
- Had some very old "international" Euro firmware flashed at one point, based on the main version. But this doesn't correspond to the radio number
Its also not clear what version of Sense, is desired: Euro, AT&T, or Dev Edition?
Going to latest Dev Edition RUU is probably the best approach. This will put the phone on Sense, devoid of any AT&T bloat or limitations, plus will update to Marshmallow. Those are all good things, plus the phone already has the proper CID for Dev Edition.
1) Run 6.12.4540.4 firmware from here: https://www.androidfilehost.com/?fid=24438995911977418
By process:
adb reboot bootloader
fastboot oem rebootRUU
fastboot flash zip firmware.zip
fastboot reboot-bootloader
Where "firmware.zip" is the actual name of the downloaded file.
2) Run the Dev Edition RUU (PC required) found at the bottom of the following page: http://www.htc.com/us/support/htc-one-m8/news/
There are other versions that may be converted to (such as Euro) if different band support is desired (Dev Edition has the same band support as AT&T version). But if that is the intent, let me know and I'll walk through that process.