Been having problems for awhile with my torque converter not locking in. Took it the shop and they put a new torque converter and selenoids in the valve body. Started working but now it’s having the same problem. Also the voltage gauge has now started staying at zero and won’t crank. Every once in awhile it will crank and after you drive around for a few minutes the gauge will go back to zero. Checked all the grounds off the batteries and they seem fine. Any help appreciated.