Thunderbolt Display and power

My 27" A1407 display won't power up. BUT, the charger cable will charge an old MacBook Pro, that has the right 'old' power connector. Does this mean the power supply is dead? Or, is the logic board dead? Or....something else?

I am pretty sure that the power supply provides charging current to the magsafe connector, so the battery charging (through the magsafe connector) might work great, but power to the display itself might not work (no video comes on)
Maybe this article might help? https://www.ifixit.com/Guide/Apple+Thunderbolt+Display+Black+Blanking+Out+Repair/175666
(repair of these displays is NOT for the faint-of-heart

DeltaMac said:

I am pretty sure that the power supply provides charging current to the magsafe connector, so the battery charging (through the magsafe connector) might work great, but power to the display itself might not work (no video comes on)
Maybe this article might help? https://www.ifixit.com/Guide/Apple+Thunderbolt+Display+Black+Blanking+Out+Repair/175666
(repair of these displays is NOT for the faint-of-heart

Click to expand...

Thanks, DeltaMac. A used power supply arrived today. I have some youtube how to's on the replacement of the power supply. I have suction cups and an OWC tool to remove the front glass. I'll do a remove/replace to see if the power supply is the problem.
I don't have enough experience to know the difference in the power supply wiring to know for sure how to get the power/screen going.
I have seen logic boards for sale as well, but we'll see how this goes...
Bill G.