I had the same problem on my Go710 and thought it was the battery that wouldn't charge up. I bought a fitted a new one, but it didn't sort the problem out. I looked around on the net and found that the problem is common when using a faulty or inadequate charger. I bought a new one on ebay (about £5), plugged it in for a couple of hours, pressed the reset button on my satnav a couple of times, and hey presto!! it's back to life!!! Hope that works for you too.
Boosh, June 2009