Phone gets into a reboot loop

[Pat McGowan]

Reported by several BQ users
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I plugged in the charger before starting the update.
The phone listed several app updates in addition to the system update (v.20), but I only requested to download the system update.
I left the phone while it was downloading. After a few minutes I unlocked the screen, checked that the download was complete, and requested 'install'.
The phone promptly rebooted, showing a large Ubuntu spinning logo. This continued for approximately 10 minutes.
The phone then rebooted showing the bq logo for a fairly long time (approximately 1-2 minutes, not sure)
Then it rebooted once more, this time into a loop where the bq logo flashes on and stays for 10 seconds, turns off and repeats.
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After changing language settings on my Aquaris 4.5 from German to English, my device refuses to boot.
Stays in boot loop, only showing the small Ubuntu logo.
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These two users recovered using the procedure at ] http://askubuntu.com/questions/602834/how-to-reset-bq-ubuntu-phone-when-gui-is-inaccessible

[Simeon (simeon5)]

Just wanted to report that I upgraded my Aquaris to r20 without problems last week and havent had any problems regarding booting of the device since.

[Cos64 (cos64)]

I upgraded from r16 to r20 without any incident, one week ago, immediately after I received the new device.

[SB (emehntehtt)]

My BQ phone got into bootloop this morning, the device froze and I powered it off and on and got into continous bootloop, I believe changing system language may be the culprit, a few days ago I changed from English US to English UK. Before the change I had another phone freeze but then it booted normally after I powered it on again. Had to do a factory reset to fix the problem and the phone was fully updated from day one running 14.10 r20.

[Leiss (dess-mlv)]

I updated from r19 to r21 directly as prompted. The upgrade went without any problem and the phone restarted normally. Later I restarted it manually in order to insert a new sim card and it went in a boot loop for several seconds. I got the blank screen with the bq logo 4 times before loading and seeing the ubuntu logo. Then I changed the language (from French to English UK) and the boot loop went for several minutes. I waited at least 5 minutes with the same repeating bq logo before getting the phone to load. Fortunately I didn't need to do the system reset.

[Pat McGowan (pat-mcgowan)]

The root cause has been found and is being worked on at bug #1447756