Hey Matt,
if Onefinity should provide you with a replacement of the buildbotics-derived Onefinity Controller, which they stated would be $500 +VAT, you will hardly get a stand-alone and nearly fully RS-274NGC-compatible 4-axis CNC controller with integrated stepper motor drivers and remote network access at a lower price. They may sell you one if you are the new owner. I would contact them per e-mail.
Most people kill their Onefinity controller by not using an adequate dust collection in their workshop and the fan of the controller draws all the dust. Wood dust destroys electronics. You could try to see if it is the version with the rocker switch (hardware controller version <=v4), if the switch has dust inside, you can find the servicing instruction to repair it here:
or here is a link to a rocker switch replacement.
I strongly suggest enclosing your CNC controller in an enclosure like this one.
Welcome to the forum!