[Nexus 5X Q&A, Help & Troubleshooting] HankB:
I'm trying to upgrade my Google Nexus 5x to Oreo. (Phone purchased directly from Google and presently on T-Mobile via Ting MVNO.) I don't seem to be getting the OTA and I guess that's because T-Mobile has not released it yet. (In the past I thought that upgrades came directly from Google so this is a bit puzzling to me.) This leaves me trying to sideload following the instructions at https://developers.google.com/android/ota.

I installed the SDK tools (on Linux Debian 9.0 Stretch), put the phone in developer mode and have put the phone in recovery mode using 'adb reboot recovery'. At this point I run into difficulty as 'adb devices' lists no device.

Contents of /var/log/messages for this process is:

Sep 27 08:37:54 yggdrasil kernel: [500679.560432] usb 3-2: new high-speed USB device number 11 using xhci_hcd
Sep 27 08:37:54 yggdrasil kernel: [500679.703784] usb 3-2: New USB device found, idVendor=18d1, idProduct=4ee7
Sep 27 08:37:54 yggdrasil kernel: [500679.703786] usb 3-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Sep 27 08:37:54 yggdrasil kernel: [500679.703787] usb 3-2: Product: Nexus 5X
Sep 27 08:37:54 yggdrasil kernel: [500679.703788] usb 3-2: Manufacturer: LGE
Sep 27 08:37:54 yggdrasil kernel: [500679.703789] usb 3-2: SerialNumber: <obfuscated>
Sep 27 08:37:54 yggdrasil mtp-probe: checking bus 3, device 11: "/sys/devices/pci0000:00/0000:00:14.0/usb3/3-2"
Sep 27 08:37:54 yggdrasil mtp-probe: bus: 3, device: 11 was not an MTP device
Sep 27 08:38:34 yggdrasil kernel: [500719.623295] usb 3-2: USB disconnect, device number 11

The last line is produced by the 'adb reboot recovery' command and there is nothing further until the phone restarts (on its own.)

I searched the forum for this issue and found two threads, one of which referred to a thread with a solution but my search foo is not up to finding that thread. :-/ Any help with getting Oreo on my otherwise unmodified/unrooted/not unlocked phone is welcome! (I'm jealous that my wife has had Oreo on her 5X via Verizon and she still thinks that Oreo is just a cookie. ;) )

Thanks!

Edit:

Before issuing 'adb reboot recovery' and after starting the adb server, the device shows up in the listing:

root@yggdrasil:/home/hbarta/Downloads# adb devices
List of devices attached
<obfuscated>	device

root@yggdrasil:/home/hbarta/Downloads#

After rebooting to recovery mode the phone shows the green android on its back with a red triangle with '!' on it. Below that in white text it states "No command".

I have also tried this using Ubuntu Mate 16.10 and Xubuntu 16.04 with the same results. (All are Debian based.)

Edit.2 I got some further help from Ting support. He suggested installing the community maintained package for ADB (vs. just unpacking the zip file.) That configures udev rules and adds me to 'plugdev' (or maybe I was already there.) It appears that the benefit of that is that I no longer need to be root to execute the 'adb' commands. Otherwise the results were the same.

I checked Developer settings and unlocked the bootloader to see if that made a difference. I think it did not.

While the phone was in recovery mode, I was poking randomly at the power and volume buttons to try to reboot it when the phone display changed to a recovery menu. One option was "apply update from ADB" which I executed. The phone screen then prompted me to execute the 'adb sideload <filename>' command which I did on the PC after verifying that the phone was now listed in ADB devices (it was.)

Download completed and following reboot the phone is now running Android 8.0.0 :) I snagged a picture of the screen after download and before reboot if anyone is curious.