Nexus5 shuts down

[A Former User]

Hi guys! Found a bug: trying to log in on Arch wiki forum from Morph browser. In parallel is opened Protonmail webapp (tried with both) because password is in my mail. Copy option works bad in webapp so I have to switch back and forth between apps. I manage to fill my username, but halfway through the password the phone shuts down with no warning. As well, the keyboard doesnt apear sometimes. Note: I have erased Onion since 1 week, data was from the SIM card. If you guys know a command that I can run in terminal to save the event as a log file so we can have a look into, that will be great. Many thanks!