check if there are outboard fuses usually near the AC power cord.
If not, they're internal and must be checked under the cover. As a matter of fact, the power fuses are usually next to AC power portion of the unit. If fuse is transparent, you can see that thin conductor is torn, or burnt. If fuse is ceramic and not transparent, you may need to use continuity tester. In fact even transparent ones you don't see conductor defect won't hurt to test for continuity.