Model MS 2327 B, works but is not heating up anything

This is a very common fault on microwave ovens and is usually caused by a failed magnetron. This is the device which produces the microwaves and it is the single most expensive component. Magnetrons don't really have a fixed lifespan, they can last for twenty years or more or can go pop the first day they're used.

Replacement is usually straightforward (make sure to obtain a new microwave collar as the old one cannot be re-used safely) but rarely cost-effective. Unless the oven remains under warranty it's always far quicker and usually much cheaper to replace the oven, especially as yours is a budget model.