OptiPlex SX270N does not boot

Hello,

my OptiPlex SX270N does not boot anymore. Actually he make´s nothing at all, ecept for a little LED that shines.

This is allredy the 2th SX270 I lose because of this and I can´t believe it´s an random mistake.
I looked it up on the web and fund comments about „defective capacitors“.
What can I do??

Thanks beforehand,
Simeyer