Do the plates and the rest of the innards look ok ? I cant image what could melt the water cooled gate like that. (Without making other visible damage of course). My fuse looked fine but it was blown per the ohm meter. The guy at the hardware store said it looked fine too. He double checked with his meter and concerred.
If the cell has no lights at all, then either the cell is bad or the power center is bad.
With the cell in a bucket of plain water, you can turn on the power center and then measure the voltage going to the cell..
The cell cable has 4 wires... The Red and Black wires carry the DC voltage to run the cell, including the lights. It should be 35 to 40 volts DC... (Note this is how my EasyTouch works, but I assume it is basically the same for the Power Center. The Power Center has a transformer which supplies AC voltage to a power supply board, which converts the AC voltage into the DC voltage used by the cell.
Not sure of the model number on the heater but it is a pentair,they also have a sta rite vs pump motor sure on exact model. There is a however a green light inside the transformer that is illuminated and the pump and cell run on the same timer. The pump works just fine and the flow switch has NOT been replaced
If the pump is a VS pump, it has its own internal timer. If the pump turns off while the cell is still powered and the flow switch is stuck in the ON position, the cell can generate a mixture of chlorine gas and hydrogen gas that can explode.
The grate might have been damaged by the heater if the heater was on with low flow or maybe there was a gas buildup and explosion. Either case could damage the cell and electronics.
Check the manufacturing date to see how old the cell is.
Check the cell cord to make sure that it's in good condition.
Check the cell control interface to make sure that it's not damaged. Sometimes water will get into the interstitial layer and short out the electronics
Check for power at the cell cord connection to the power supply.
To me the plastic grate looks discolored along with the melting. Mine is glow in the dark / pure white. It looks burnt to me. But not in a hot water kind of way, more like an electrical charge or explosion. My guess is either the plates somehow arc'd and blew (power surge/lightning) , or it was running without flow and exploded, but only a little, not enough to send shrapnel everywhere.