Could be from improper cooler installation. Cooler master ML360R uses the Stock AM4 mounts. It will warp the board a bit if you over tighten the thumb screws. That little bit of warping will partly lift the heatsink on the VRM cooler and cause it to burn out.
Symptoms of a damaged VRM include thermal shutdown, rebooting and a very unstable PC especially when loading any CPU intensive program.
B450 Tomahawk doesn't have the best VRM config to begin with. Any overclocking will overheat the VRMs and running a Higher end Ryzen 9 5800x, 5900X or 5950X will cause the motherboard to quickly fail because of there higher voltage requirements. I read a bunch of reviews on the B450 boards and they run really hot especially if you run a 100-125W+ TDP chip in them.
B450 comes with 4+2 phase setup where as the B550 comes with a 10+2+1 phase setup and the X570 comes with a 12+2 or a BEEFY 14+4 phase setup. However the X570 boards all have those small Garbage chipset fans on them that tend to fail after a couple years.
I bought my X470 before the B550 boards came out because 3rd and 4th gen Ryzen wasn't officially supported with the B450 and I did Not want another board with one of those Garbage Chipset fans on it. I got my MSI X470 Gaming Plus MAX for $120 and it's very good for a Budget Mid-range motherboard that supports 3rd and 4th gen ryzen. 4th gen support came in a Bios update. I'm running a 3rd gen Ryzen 7 3700X 8 core 16 thread cpu. I really need to get a better cooler though. The stock AMD Wrath Prizm cooler works very well but it is loud as heck.
I would recommend getting an MSI B550 motherboard if you can find one at a decent price. Motherboard are starting to go back up in price again.