Do you get anything from the console after cycling power to the chassis or performing an OIR on the misbehaving RSP? How about if you remove all modules except the RSP (in case another module is shorting/jamming a bus).
If these do not work, have you tried moving the RSP to the alternate slot in the 903 chassis? If it works in the alternate slot, you probably have a chassis issue with the original RSP slot. If it also fails in the alternate slot, it could be either an RSP issue or still a chassis issue, but that can be settled if you have a redundant/spare RSP that works in one or both slots.
Bottom line is that if your RSP has an issue and does not provide any console output, there is not much you can do except open a TAC case for an RMA (provided you have a support contract and this is not an EOL RSP1).
Disclaimer: I am long in CSCO
