2006 master warning light

Okay, so I recently (Feb. 2020) bought a 2006 Prius. The car hasn't had any issues until last night when the master warning light came on. Along with that, the cruise control cut off, I can hear a fan running in the back constantly when the car is on and it won't accelerate very well. Is there any hope that this is something other than the hybrid battery needing replaced? The car is in need of an oil change, but because of Covid we haven't taken it to get done.