Try disabling "Don't keep Activities" from the Android settings.

Press the home button Press the menu button Select settings scroll down to the Developer options scroll down to "Don't Keep Activities" and uncheck it

Some have reported that pressing F9 and the Windows key simultaneously one or more times has worked to fix issues with the keyboard not working.

You can check if you can start Firefox in Safe Mode by holding down the Shift/Options key.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes