Hate to review an old thread, but I've got serious issues here.
6.1.9 was running fine, 'Upgraded' to 6.3.2 and was unable to connect after a restart. Tried all the options above and eventually running out of options, having copied the files from my USB to the PC (post the upgrade), I restored them to the USB stick, replaced the latest files with those from the previous folder, stared the server and when the options come up it's saying 'Automatic boot in 5 seconds...' it then counts down and goes straight back to 'Automatic boot in 5 seconds...' rinse and repeat.
There is a brief message along the lines of 'Booting Kernel failed: Invalid Argument' as it loops
Any ideas?