Assuming that all the fuses are OK and there is no visible internal damage since you took the unit in for service, Here's a few things you can try.
Swap all speaker, IC and PC's connected to the amp with something else to confirm that you don't have a cable problem.
Plug the amp directly into the wall.
Plug the amp into a wall outlet on a different circuit than it is now. Use an extension cord if you have to.
Undo any recent changes that you made to your system.
There's other things you can try, but I would start with the above first. I thing there's a pretty good chance that something is wrong with the wiring in your house, and you're not aware of it. Maybe a wire is corroded or an animal did some type of damage. The results of this can be that you are getting less power from your outlet, forcing the amp to go into protection mode. Also, it would be a good idea to unplug your amp from the wall, and any cables connected to it, until you are able to locate the cause of your problem. And if it does look like your house wiring is at fault, have someone look at it right away. You can have a fire or do damage to other electrical devices in your house.
Swap all speaker, IC and PC's connected to the amp with something else to confirm that you don't have a cable problem.
Plug the amp directly into the wall.
Plug the amp into a wall outlet on a different circuit than it is now. Use an extension cord if you have to.
Undo any recent changes that you made to your system.
There's other things you can try, but I would start with the above first. I thing there's a pretty good chance that something is wrong with the wiring in your house, and you're not aware of it. Maybe a wire is corroded or an animal did some type of damage. The results of this can be that you are getting less power from your outlet, forcing the amp to go into protection mode. Also, it would be a good idea to unplug your amp from the wall, and any cables connected to it, until you are able to locate the cause of your problem. And if it does look like your house wiring is at fault, have someone look at it right away. You can have a fire or do damage to other electrical devices in your house.