iPhone 3G Model a1241 not responding on any function

HI, I have IPhone 3G Model a1241, It was functioning slow so i planed to soft rest it but after rest my Iphone is now not turning ON. I have also t... HI, I have IPhone 3G Model a1241, It was functioning slow so i planed to soft rest it but after rest my Iphone is now not turning ON. I have also tried the home button and power button combination but no responce. Then I put it to charging and it is giving Yellow screen on start for approx. 50 sec and then the apple logo come and stays for approx 4 minutes. Then reboots and the same yellow screen and again apple logo. Please suggest what can fix this issue, Waiting for a solution from experts. Thanks in advance