[G2 General] _LeoDJ:
Backlight blinking / phone always disconnects

Hello,

first of all thanks for the guide. It sounds like it would work very well.

But sadly I can't even follow step 1. If I plug in my phone to my linux pc (running Kubuntu 16.04) it boots, shows the secure error message and then the backlight always turns on for ~2s and off for ~0,5s over and over again, no matter what I did.

This wouldn't be so bad if it would connect for any time at all. If I spam "ls /dev/sd*" in the terminal after maybe 30 executions and 4 backlight blinks I get the 36 Partitions on device "sdf".

So there is a connection for a few milliseconds. If I then run "gdisk" (20-30 times until I hit the exact time when the phone actually connects) I see the partition list fine.

Basically I'm having the same issue as vlourie here, but if I run Ubuntu (16.04) in VMware (on Windows) and forward the USB connection, my G2 is doing the same backlight blinking again.

I also tried it on my laptop with a live Linux USB stick, but still the same thing happens.

In a last attempt, I tried if it would be possible to dd something during those few milliseconds. Obviously I didn't try to write anything to the partitions, I tried to copy sdf2 into a file. (again, spam command 30 times until it hits the right moment) and it did transfer something, but the .img file is only 112KB big. Not the 512K it should have been. The same thing happens for any other partition, I only get 112K of data.

Which means, that the connection definitely isn't going to last long enough to transfer a 1MB image.

If it helps, I was simply trying to install Magisk with the official installer app and after I did the prompted reboot, I got the secure boot error.

Can anybody help me recover my trusty G2 or at least point me into the right direction? Not many people in this thread seem to have the same problem as me and any help is appreciated.

Thank you in advance!

tl;dr: Phone backlight keeps blinking and only connecting for a fraction of a second to any Linux system, not long enough to run any dd command

Edit: In case it helps anyone, here is the dmesg output:

[ 196.720998] usb 1-1: new high-speed USB device number 44 using ehci-pci
[ 196.916890] usb 1-1: config 1 has an invalid interface number: 20 but max is 1
[ 196.916893] usb 1-1: config 1 has no interface number 1
[ 196.924865] usb 1-1: New USB device found, idVendor=05c6, idProduct=9006
[ 196.924867] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 196.924869] usb 1-1: Product: QHSUSB__BULK
[ 196.924870] usb 1-1: Manufacturer: LG Electronics Inc.
[ 196.924871] usb 1-1: SerialNumber: 1234567890ABCDEF
[ 196.928304] usb-storage 1-1:1.20: USB Mass Storage device detected
[ 196.928353] scsi host75: usb-storage 1-1:1.20
[ 197.930513] scsi 75:0:0:0: Direct-Access Qualcomm MMC Storage 1.00 PQ: 0 ANSI: 2
[ 197.932461] sd 75:0:0:0: Attached scsi generic sg3 type 0
[ 197.942196] sd 75:0:0:0: [sdb] 61071360 512-byte logical blocks: (31.3 GB/29.1 GiB)
[ 197.948285] sd 75:0:0:0: [sdb] Write Protect is off
[ 197.948289] sd 75:0:0:0: [sdb] Mode Sense: 0f 0e 00 00
[ 197.953236] sd 75:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 198.046350] sdb: sdb1 sdb2 sdb3 sdb4 sdb5 sdb6 sdb7 sdb8 sdb9 sdb10 sdb11 sdb12 sdb13 sdb14 sdb15 sdb16 sdb17 sdb18 sdb19 sdb20 sdb21 sdb22 sdb23 sdb24 sdb25 sdb26 sdb27 sdb28 sdb29 sdb30 sdb31 sdb32 sdb33 sdb34 sdb35 sdb36
[ 198.096372] sd 75:0:0:0: [sdb] Attached SCSI disk
[ 198.368503] usb 1-1: USB disconnect, device number 44
[ 198.372793] sd 75:0:0:0: [sdb] Synchronizing SCSI cache
[ 198.379926] sd 75:0:0:0: [sdb] tag#0 FAILED Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
[ 198.379930] sd 75:0:0:0: [sdb] tag#0 CDB: Read(10) 28 00 00 00 00 80 00 00 90 00
[ 198.379932] blk_update_request: I/O error, dev sdb, sector 128
[ 198.380125] sd 75:0:0:0: [sdb] Synchronize Cache(10) failed: Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
[ 198.380187] Buffer I/O error on dev sdb, logical block 16, async page read
[ 198.380210] Buffer I/O error on dev sdb, logical block 2, async page read

this block of error repeats with every backlight on/off cycle