2010 ss RPD Guage says "safe mode"
 

It's all blacked out and says safe mode in the top left corner. I took it to the dealer and they have no clue what is causing it. No codes came up. I'm gonna disconnect the battery when I feel like pulling my subwoofer out but just seeing if anyone knows the cause or fix for this.

Stock sub or aftermarket? Reason I ask is that if you have an aftermarket sound system, I don't have a copy of the factory service manual right now to verify wiring, but I thought the stock head unit also connects to the vehicle's CANbus to read vehicle speed for the speed-compensated volume. The reconfigurable performance display also rides on the same CANbus to talk to the engine controller and get sensor data.

I haven't heard of that error with the RPD before but if there's a problem with it's data connection it might be reasonable to assume it can't power up and pass a self-test or something similar. You don't have anything else connected to the OBD-II port?

It's an aftermarket sub. I've had this set up for at least 4 years now though. So I don't see why that would cause an issue now. Nothing else is connected to the OBD-ll port.

If it's just a sub, then no, probably not related. If it was an aftermarket head unit with one of the adapter harnesses where the wire for the data link that goes to the stock head unit had shorted out or something it might cause a problem with the gauge. Disconnecting the battery might be good like you mentioned and possibly pull the pillar/gauge to make sure the wiring has a good connection.

Still in safe mode. Any ideas?