Reviving M5 after long storage

Long story, but my M5 has been in storage in a sheltered but non-climate-cotrolled garage for more than a year, with some pla filiment in it. Like, it finished a print, and then without anything being done to it, was moved into the garage.

I've never been in this kind of situation, and want to get out of it without problems. What do I need to do to get it back in good working order without mishaps?

Is it as simple as letting it heat up pull the filiment and put in some new, dry filiment?