Tried to upgrade TWRP before upgrade to LOS 17.1, now stuck in boot loop! Help!

[AnotherElk]

@perolalars

LOS splash animation comes up and goes for a couple of minutes and then boots back to TWRP.

If you still have the install file for the LineageOS build you currently have on the phone, just install it with TWRP again over the existing installation. This doesn’t do anything with Apps or data … helped me a couple of times out of a not booting OS after a TWRP backup restore.

@perolalars

And another very annoying thing is that I can´t access the phones storage, not internal or sd card. My pc gives a notice when I connect the phone with usb cable but its not showing in the explorer.

You need to boot into TWRP for your PC to see the phone’s storage.
If this still doesn’t work …

@AnotherElk

• Disconnected the phone from the computer.
• In Control Panel - Programs and Features:
  Uninstalled everything with “MTP” or “ADB” in its name.
• Rebooted Windows.
• In Control Panel - Device Manager:
  Enabled View - Show hidden devices, and then uninstalled every possible ADB, MTP and smartphone device, hidden or not.
• Rebooted Windows.
• Connected the phone again with booted TWRP, Windows then needed a moment to set up MTP again automatically and prompted a success message afterwards.

Et voilà

@AnotherElk

Turns out I deleted my working dic:adb and dic:fastboot commands with this endeavour (they were probably from Minimal ADB and Fastboot), so I did the following …

• Downloaded the current Android SDK Platform Tools, it’s better to use these anyway.
• Unzipped the ZIP file to C:\platform-tools (you can unzip it to wherever you like).
• Added this path to the Windows “PATH” environment variable, so adb and fastboot could be run from everywhere again without always having to prefix them with C:\platform-tools\ .