I may have had a similar issue -
1) 6.1.9 ran fine.
2) Upgraded. 6.2 took forever to load bzroot and then started giving me "device descriptor read/64, error -71" errors for the usb drive and then hung.
3) Downgraded. 6.1.9 ran fine.
4) Used another usb stick. 6.2 gave me the same errors. 6.1.9 ran fine.
5) Finally (knowing that -71 errors could be indicative of usb hardware issues), I disabled the USB 2.0 controller and BINGO - it booted fine
I'll keep playing with it when I have more time but I'm fairly confident it's a hardware issue. No clue as to why 6.2 suddenly puts it in the spotlight. I also haven't tried the gui version.
As I prefaced, I can't tell if your issue is same as mine but try disabling the USB2 controller and see if it boots.
cheers