recovery mode loop, restore 06.15 iphone. please help.?

[LauraAnderson]

i have tried to restore back to factory setting so i can start the whole process of jailbreaking and unlocking again to see if it works but now i cant restore as ive upgraded to 06.15 and i get error 1015, so now im stuck with a phone in recovery mode and the only option i have now is to connect to itunes and restore where i am then greeted again with the error 1015 message. im on firmware 06.15 and version 4.2.1.i understand that the error message is because i have upgraded to 06.15 and i cant come back down from that. i have tried downloading firmware 4.1 but when i try to restore through itunes it says firmware not compatible. please if you have no knowledge of iphones then please do not answer. any help would be great.