LG 42v6 Plasma Lower Y PCB Question

[neTWork2008]

Hi,
Working on a Hitachi Plasma with the LG 42v6 PDP.
The display has a vertical data copy problem.
I disconnected the lower Y driver PCB to see if it was causing a problem.
As expected the upper half of the display and the data copy problem remained but there was also several inches at the bottom of the screen which was also being scanned?

I expected the lower half of the display to be blank.
I switched off and thought about the problem then made the mistake of switching on again. This time there was no scan / display.

To cut a long story short one of the driver IC's on the upper Y driver PCB
was visibly blown.

I know there were no shorts or other reasons for this IC to blow.
My question is:
Is it an unsafe method to faultfind using this technique?
Is it risky to disconnect the lower Y PCB in this way on a v6 PDP
Was I just unlucky?

Time to find a replacement upper Y PCB.

[minnie]

Y DRV UPPER B/D ASSY 6871QDH066A.