You've already done what I would've done - remove all accessories. Next I would swap out the power supply, if you have one laying around. If not pull one from a working server. If you don't have any of those luxuries then it gets challenging. You would have to start buying parts, etc. -- you see where I'm getting with this.
OR (I assume you don't have contract) purchase the cheapest coverage contract and see where HPE support takes you
~B
