I167 cover removal

[Tom52]

Hey,
I thought this would be an easy search - but I'm coming up empty somehow. I have an I167 that was supposedly good except for the batteries. I got some good batteries off ebay and everything worked fine on a few rides over the period of a month or so. Then I parked it for a month - plugged in though. When I went to ride it again - no display and a beep when the key is engaged. I removed the batteries and one reads 74 volts or so and the other reads 8.6. So - I'm screwed it seems. I have a few questions to get me to the next step;
1. when the unit is plugged it with no batteries installed - should I be able to read voltage at the battery connection pins on the bottom of the Segway? If so - what should the voltage read with no batteries installed?
2. How do I get the top cover off to see if I have loose wires? I've removed all the screws on the top including the 3 on the handle mount. I also removed the nut inside the handle mount (the one the cable goes through).
3. Any ideas how a unit just sitting that was fully functional could end up with one battery at over 70 volts and the other around 8?

Any ideas/thoughts are much appreciated. I'm $1500 in now and have a marginal boat anchor at best
Thanks
Tom