Just do the quick fix of the Tuner, that has (original or clone it's same), after some time (YEARS) the Capacitors that get bad.
Check the 4 big capacitors on motherboard, if they have hills change then and the box will work again for more than 5 year or even 8 as the DM800HDpvr is from 2009.
Check also the PSU, as these fail after few years, not giving enough Amp... important to have at least 3 Amp.
If it's the tuner, the J model is the exact replica on the clones of the Original tuner (then a variant is the K, mostly same), that fails due to capacitors, that is fixable. There is a cap to add to get the HD channels working (when you can watch only the SD and not the HD).
Anyway, it's great hardware, as it's fixable, all cheap Enigma2 new boxes now get scrapped as very bad hardware (only ones that are worth are DM and VU), the old DM Original or Clones have great hardware and caps replacement generally fixes all.
TS
On my dm 800 sim 201 using openpi, the box everyday in 24h loose the signal.
When work its ok but it looks like if the box goes on for to long the signal with soon gone.
I nearly got this box and its very strange,
Any idea what could be the problem...