First the original poster I sympathize with all the frustration of your scanner not working up-to to par; I to have a BCD536HP. First I think your main problem with the RTC battery is serious enough that Uniden should issue a Recall, if not a fix for the problem RTC, secondly and you're gonna think this is absurd but follow me; you'll need to USE the scanner and Sentinel in conjunction, SAVE SD card in SENTINEL then go to the scanner and CLEAR USER DATA, in Sentinel ERASE FAVORITE LIST IN SCANNER and FORCE WRITE FULL DATABASE reloading RRDB and Favorite list, if that doesn't stop the constant reboot condition try to Reformat the card in Windows and try all steps again, lastly if that doesn't work you probably need a new card. I personally use a SanDisk Ultra Plus Micro SD 16gb
SanDisk Ultra Plus Micro Secure Digital High Capacity microSDHC Memory Card 16GB by Office Depot & OfficeMax , it is fast when I load my Favorite list with 45 Systems and about 1300 TG/Channels, only one Quick Key is enabled ON.
What ever you do don't let the BACKLIGHT stay set to HIGH, there is no real heat dissipation from the upper L.E.D.s the inner and outer case block the heat and the lower L.E.D.s have 5 Wide buttons and the possibility for heat to escape from there, or rise to the Upper L.E.D.'s, as well as they maybe overdriven with voltage at the HIGH setting
Short of Soldering in a New Battery Holder for the RTC problem and/or Drilling holes to allow heat to dissipate from Upper L.E.D.s, or using a seperate light, the 2 things will continue to be problematic for BCD536hp and BCD436HP Owners sooner or later
I'm truely sorry about the level of frustration and consternation that you feel about your scanner, just take comfort in knowing your not the only one.