If you haven't called Mits yet, do so. Tell them you live out in the boondocks and no service facility is near enough. Get a incident (reference) number, or whatever it is called. Then ask to speak to someone in California (possibly a 2nd phone call). Ask them to ask their 'advisor' what other board could be replaced instead of the whole Light Engine this so called 'tech' said was needed, since you are the one paying for this.
Abundant OTA television is what makes this country different from all others. Lets keep it this way. If you like Wi-Fi so much, OTA fits right in. After all, it is wireless.