Haven’t used iPad for 2 years. Forgot passcode. Downloaded iTunes, restore to factory failed, with error '''0xE8000015.'''
Downloaded 3u Tools, flashed firmware. 3u Tools wasn’t able to connect to iPad. Flashed firmware again. Still couldn’t connect after flashing, can’t restore on Windows 10.
Connected to iTunes in MacBook, restore failed again.
Connected to iTunes in Windows 10 again, iTunes gave message that iPad was in recovery mode, asked to restore. I clicked ok, iPad restored to factory.
Now I think I remember what the passcode could have been. I don’t know if there’s a way to enter this old passcode to recover the data that was in iPad before factory reset. At least I now have a working iPad.