I haven't read all postings here, but I think I have a/the same problem (now). My SD49225T-HN from Feb. 2018 now (since a few weeks) also boots several times (maybe five times) a day.
![Frown :( :(](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
How many times a day does this happen to you?
I already use a 12V power supply from the beginning. Until today I used an old firmware version from 2017 all the time. Today I did an update to 2.623.0000000.7.R.R4.2510.9A.NR, Build Date: 2018-11-24, but just now I have the first reboot again.
![Roll Eyes :rolleyes: :rolleyes:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
I`ll keep watching over the next few days/weeks ...