Due to the extremely high resistance the circuit would have caused as a result of the very dirty cell, it's entirely possible it fried something in the power supply or the controller itself.
Before I get started, I did find this wonderful tip on cleaning these cells.
From Hayward/Goldline themselves.
The cells: Over acid-washing will prematurely kill a cell. Take it off every 2-3 weeks, spray it out with a high pressure nozzle and hold it up to the sun. You should be able to see through it so clearly that all you see are the plates hanging down. These cells are
PRICEY! Protect your investment! To remove the deposits, use a 4 parts water to 1 part acid mix. If it's still bubbling after 30 minutes, 3:1, never stronger than 2:1, and only when necessary (preventative maintenance...). And never just set it in a bucket of even the mildest acid solution if you can't check on it FREQUENTLY. If you never find scale inside the cell, start stretching out the time between checking. You'll figure out how often you need to check yours. This new cleaning method was released by Goldline, based on their examination of returned cells.
I haven't actually used one of these Hayward cells, but I know electrolytic cells and how they function. The 1st thing I would do is to test the voltage of the output lines to the cell, coming from the power supply. The system should measure at 24v according to HW spec. If you have a way to tap into the circuit, or test the terminals on the plug while it's running, do that using a multimeter set to DC range, it's not AC. Check for idle & cell operational voltage.
If that checks out, then hook up an amp meter in circuit/series, not parallel (probing), T-15 cells are 4-8 amps of power draw.
AMP Meters are polar specific, but if you hook them up backwards, then it just reads negative, no biggie. Won't fry it. I have found those cheapo digital meters at hardware stores made by Gardner Bender to be really useful as they go quite high on amps before blowing, at about 15-18amps IIRC. They cost about $10.
They go much higher than most expensive meters, even my crazy over priced, but very well made Fluke DMMs and these cheepies are only "rated" for 10amps.
Just hook the positive red meter lead to the "current source", the controller voltage output to the cell, then hook the black negative probe of the meter to the destination, your cell power connector. Some circuits are backwards. Again, doesn't hurt anything, just gives a negative instead of positive reading on the meter.
To hook it up, just get creative with leads and electrical tape. No need to solder, just twist the wires together, make sure things don't touch where they shouldn't, or ground to nearby objects. Take apart an old electrical cord or something and use that for leads. Be creative.
Once you hook it up in-line, then you can run the cell and see what kind of amps she's drawing. If it's very little in comparison to what it should and the power supply checks out, then odds are you have a bad cell. But I bet that's not what you'll find, what I'm betting you'll find is a proper amperage draw, indicating a bad controller.
I suspect your cell is fine, corrosion wise, IE. any ill effects from the oxide. Reason being is I highly doubt they'd go to the trouble to use Ti plates in the cell, then bolt it all together using stainless or normal steel bolts that can rust. Yes, stainless rusts, mostly in electrolysis, not to mention it generates Cr6, which is very carcinogenic. That's as far as the cell itself goes, I know there is a salt sensor or some sort of sensor in there, from what I have read, but that should throw an error if it were bad. IE. Low salt, high salt, salt reading doesn't match your readings, +/-400ppm, etc..
Here are some things to read up on, regarding repairing your controller, which is advised if you're handy, since they run $700+ end user price from a dealer/service tech, $450 or so if you buy one yourself and hunt for it.
Do make sure the controller still knows you have a t-15 cell hooked up and not one of the other units.
Also, take the amperage reading that the controller is telling you and multiply this time 4 to get the number of grams/HR of CL being output.
I forgot to ask, how are you checking the CL output of the cell?
PS. Sorry if my post is a bit disjointed or scatterbrained, it took me a bit to compile all of this and it got late on me, brain isn't quite working 100% yet from still getting over the flu, plus being tired on top of it. HAHA Fun combo!
So I can clarify more tomorrow if need be.
Note, you're going to need to be not afraid of wires, voltage and electronics, as well as have some experience doing this sort of thing in order to perform the above tasks. They're meticulous, require some precision and patience, but it isn't an impossible task by any means. Computer power supply connectors and a blade are your friend. I can see from the main plug cell>board that I found a picture of, one could easily build a pigtail out of an old, sacrificial computer ATX power supply harness. But probing in wires should suffice, checking to see what each does 1st at the board.
Here are the links.
This page has all sorts of diagnostic info, including how to verify that the board is good and other great tips.
It is in French though, but Google Chrome translates that well.
http://www.manulabo.com/Hayward/aqrsearch.htm
Here's a site with great pictures from a guy that repaired his after a big power surge.
http://idoneitmyself.wordpress.com/2009 ... lightning/
This website has a step-by-step how-to on performing a common fix for these units, saving you piles and piles of money.
http://www.nocellpower.com/