Core Issue
Boot loops are usually caused by insufficient memory in the router for the Cisco IOS Software version.
This is a typical error message during the boot loop:
Unexpected exception, CPU signal 10, PC = 0x60364244
60364244 60362E40 6041AAFC 6041AB74 60419870 60419B80 604261F4 60425394 604261D8 60425394 6041CF0C
The router may get stuck in a continuous loop, which may be caused by a hardware issue. A continuous loop does not allow you to gain access to the router. The router continues to display error messages until it powers off.
Resolution
To resolve this issue, use a Cisco IOS Software image that fits the platform memory, or upgrade the router memory to meet the Cisco IOS Software requirement.
For more information, refer to the Continuous/Boot Loop section of Hardware Troubleshooting for the Cisco 3600 Series Router.