Bit of an odd one….. if the LEDs operate, then the problem must be with the cells, but that’s very unusual.
I have to suggest that the best thing is send it to me and I will fix it…. setting up the stereo compressor is not too easy.
I charge a fixed £25 plus the cost of returning it to you. I’m happy to send you replacement cells, but I think it would be more efficient to send it to the Sound House!