Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble.
You are correct, unfortunately, that the unit is probably effectively shot. This is sadly a fairly common fault on this model (and several others), which stems from either corrputed firmware, or faulty eeprom (chip).
Unless it happened as the result of trying to update the firmware, then chances are it can't be resolved, as it is an underlying hardware fault, but what we can try is a microprocessor reset, just to be safe.
press and hold the ENTER button on front while powering back on,
if it will let you, use the preset <> buttons to select Reset, Enter,
Enter again to confirm.
Power off and back on
If the fault continues, that would confirm a hardware defect, which would ultimately require repair/replacement.
It certainly won't make things worse to try what you're suggesting, though to be honest I've never seen it be successful. It isn't a simple matter of a bad solder joint, it is an internal failure of the integrated circuitry, which would have to be replaced entirely (though you'd never find the part), and ultimately replacement will usually make more sense than repairs, for a 4 year old model that is essentially at the end of its service life anyway in another year. You'd be in the $650 range to have it repaired (replacing the main board).
If you'd like, I can help recommend replacement options for you though, find a repair shop, etc.
Best regards, ***** ***** for the news,
I am an independent technician and I've spent my personal time, unpaid, in an effort to assist with the question for which you solicited my services. This site works on the honor system, and to that end, I have prioritized working with you ahead of other paying customers.
Although you’ve already paid your fee to the site, I am only compensated for my efforts when customers such as yourself leave positive feedback for my work. Again I apologize there is not a better outcome here, though this is really beyond either of our control. I do hope you’ll consider leaving a 5 star rating for me, rather than “shoot the messenger”, so that I may get credit for my time spent in good faith to answer your question accurately.