I had been recirculating cold PBW through mine multiple cycles every time and it would always come out at least some shade of green. The last few batches I've recirculated 180 degree PBW and 180 degree sodium hydroxide. Rinse, PBW, rinse, Sodium Hydroxide, rinse. Water that comes out after that has been perfectly clear. Make sure you switch the flow so it goes through the chiller both ways for each step.
I've heard that baking and pressure cooking you need to watch out for the teflon tape sealing the pipe threads, but I haven't done this. It's possible that that was only if you run it through the cleaning cycle on the oven.
Simply baking or pressure cooking will not hurt the plate chiller itself.