Yeah it's a hardware fault, I've had a few of those fixed by Bowens over the years. They had to replace a board so it worked out quite expensive and of course is no longer an option with Bowens gone, sure you could find a company to replace the parts but they'd just be sourcing them from used donors so you may as well buy second hand instead as it'll probably be cheaper and it's not like they can really guarantee the work.
You'll probably have a hard time finding a 250R as they're relatively rare compared to the 500r, if one does pop up it should be nice and cheap due to how much more popular 500 W/s heads are/were, if you don't mind the older Esprit Gemini or the Gemini Classic they're often pretty cheap too but I'd look at brands like Godox first as eventually the Bowens kit will give up the ghost (R's are up to 30 years old now right?), it's surprising how much Bowens kit is still available and you do have options like Phoxene for replacement tubes but I'd have thought Godox etc are probably an easier option at this point.
