Something similar happened to me with my Flagstaff pull trailer. A loud bang then RIP microwave.
I priced Magic Chefs then quickly ruled that out. I took the dimensions of the microwave height, width, depth and found something on special at Target for $50. Red! Really added some color.
As long as the microwave is no larger than the opening of the decorative flange(?), escutcheon plate(?) cover(?), a no-name replacement will work, though you may have to slightly adjust that decorative cover when screwing it back on. Don't worry about the new microwave being an inch or so smaller all round. Once installed, it's pitch black back there, you don't notice it.
There is an anchor bracket that screws into the back of the microwave. I think I had to drill a pilot hole into the back of the new microwave to get things lined up. Check to make sure that you have a screwdriver that fits those screws.
If necessary, swap out the feet to get the replacement at about the same level.
It was relatively straightforward, and I can barely figure out how to get the lid off the peanut butter jar.
2016 Ford F350 Diesel Dually
2020 Sandpiper 368FBDS