milltronics centurion 5 fault

I have been helping a friend with a milltronics centurion 5. My machine control experience is low, but I have a background in electronics. I have repaired a few welders at component level, so I thought that I would try to help out.
He had received a repaired servo board, and as soon as he installed it the cap on the board near the bridge rectifier exploded. Turns out the 10uF 150V cap had been installed backwards. It removed a small amount of the board trace as well.
I replaced the cap, repaired the component side of the trace, the board was re-installed, and no happiness.
The Milltronics Centurion 5 reads out positions, but the machine will not home.
The display will indicate drivers on, and as soon as you tell it to home, the display shows "homing x axis and homing y axis" then 400 error and the drivers toggle to off.
Is this indicative of a driver board problem?
The limit switches both operate, if you travel past them the display indicates that they had over traveled.
Where should I look next?
Thanks
Paul Sperbeck

you have dc drives on that machine you can interchange the two drive boards just the connections and that will help you to isolate the bad board or motor you also have fault lights on those boards. good luck