Nitecore D10 R2 problem

I have an Nitecore D10 R2 that I've had for over 2 years. It started acting a little crazy last year around this time and soon would only come on and put about about 1/3 of its normal output and I couldn't get it to ramp up or down. I had put it in a drawer without a battery and forgotten about it until the other day. I put a fresh battery in and now can't get it to come on at all. Nothing has leaked in it and I tried cleaning the contacts. I had run the cheaper Energizer Lithium batteries in it for a little while before it went crazy. Any thoughts or suggestions would be great.

Thanks in advance.