When set to TV, it
Ok you need to try a channel reset, turn off leave for 5 mins or so, do this this & it may clear any faulty data in the PROM of the unit,(This too can cause it to freeze and lockup) Also have a look in the manual, you maybe, I cannot remember for this exact model? able to do a factory reset, if so, also try that first.
However, and if this doesn't work, then you have a CPU & tuner fault. I have seen this problem before, with these models, and, the faulty tuner locks up, the CPU,(Or other way round?) and will not scan. The module must be replaced. This isn't a DIY task, it must be done by a serviceman. The cost maybe a couple of hundred bucks, more if the power supply is involved too,it sometimes is?
The best thing to do,is get a "Quote' from an authorised professional, and go from there?