Hi, as I can see you already tried several steps. And you found the PERC is faulty. You can try to reset iDRAC and drain flea power but if they do not work I would suspect hardware error and consider to replace the PERC.  Manually hold the “i” button down for 30 seconds to soft reset the iDRAC. Power off the server and unplug both power cables from the power supply units . Hold the power button down for 20-seconds to clear any residual current from the motherboard. 

Thanks @Dell-ErmanO 

If resetting iDRAC is the only option left to try (which I did by the way but forgot to mention) it means I need to replace the PERC.

By the way, would replacing the PERC destroy the existing RAID array and therefore the virtual disk and the data stored on it?

Hello,

If the disks are ok and the array in intact, you should be able to Import your drives from a foreign configuration in the replacement controller when powered up.

If it doesn't automatically import, then you can go in the controller BIOS and Import.

You should not Clear the foreign configuration, you want to Import it.