I would recommend searching on Amazon or eBay for replacement parts. I was able to find a battery on Amazon for another UltraTab model. I cannot confirm whether the dimensions are the same however. Here is a used one for the C855 on eBay. You can find screen replacements on Amazon and eBay as well. Motherboard replacements may be more difficult to come by. Sometimes you can find a broken device for sale on eBay with the working component you need.

You can find the answer to this and many more frequently asked questions on Digitac's support page.

There are several reasons why your tablet may not be turning on. Please refer to the section "UltraTab won't turn on" in the troubleshooting guide.