Avoid YouTube "teardowns" for this model. Most videos show the wrong revision. The X2 2500A had three major hardware revisions (Rev A, B, and C). A Rev B manual will lead you to the wrong test points for a Rev C board.
Based on common service calls, here is what the manual would tell you to check first: carrier x2 2500a service manual
Even experienced techs fall into these traps: Avoid YouTube "teardowns" for this model