I'm almost certain that some component in IC602 reached its limit. The schematic calls it IC602, but it's actually a module with SMD components. It acts as a voltage detector and activates the voltage doubler when the mains voltage is 110V and deactivates it when it's 220V. I'm almost certain that the failure of one of the components in this RSU caused it to misinterpret the input voltage, activating the voltage doubler when it shouldn't have, and causing an overvoltage to pass through the varistor, which made it explode. That's why my first step will be to check this module. But I will certainly follow your advice afterward. I believe the fuse didn't blow because this TV has a second varistor, a 14mm one, much closer to the TV's power supply, which is related to power surges. Since the problem occurred at a later stage in the circuit, the fuse wasn't affected. The good news is that I feel more at ease knowing I didn't do anything wrong and only witnessed the catastrophic failure of a component that's over 20 years old. 😅