I jailbroke my iPad iOS 4.2.1 (tethered) and updated mobile substrate, Cydia asked me to reboot my iPad and i did. iPad stuck on Apple logo for 3-4 minutes then turned off and booted again but again didn’t surpassed the Apple logo for 3-4 minutes and cycle continues. I tried hard reboot but no luck. Then i tried “just boot tethered now” and it works like charm.
Instructions :
1. Launch RedSn0w 0.9.6b4 and select the file. ipsw firmware 4.2.1 on clicking the browse button.
2. From the next screen, select “Just Boot ...