Hi Neil,
Yes, the default OGN login is still ‘pi’ and Yes, earlier updates could have reset the password. Have you tried the ‘default’ password 12345678 ?
If that doesn’t work you do need to do a fresh install. No idea why your new upload is crashing at 21Mb though, sorry. Possibly corrupted during download / transfer or a faulty card? If so, you need to do a Full Overwrite reformat of the card and try again or try another card. (Make sure it’s formatted as FAT32.) Hope this helps.
Regards
Peter