[MikeKL]

Last three or four nightly releases I have been having total lock ups of kodi and libreelec a few moments after 1st boot up of latest nightly.
I have to physically disconnect power and then re-appy power to restart Liberelec and kodi, where everything then appears ok after second boot of a latest nightly?

kodi.old.log is always empty, is there anything else I can do to catch any info on what could be cause of complete lock-up
(ssh and remote access unavailable when lock-up occurs)

Without ssh I'm not sure what to suggest - are you able to pin down the exact build when this started, or could it just be a failing SD card? Maybe try a backup of your current install on a new SD card. I've not had any stability issues with my own RPi devices and these builds.    

Thank you for response, just to mention that since last post, installing builds #0709 through to #0712, I have not had further lock-ups after 1st boot...if problem re-appears will look into switching to another SD card.
(Not attempted to go back through previous builds as latest not exhibiting previous issue)

Did wonder if higher ambient room temp on day/evening of specific build download and instal from settings option then lock-up might be a factor.  However general running core temp of my rpi3B+ according to bcmstat currently 54.77C (iplayer www, streaming tennis match @ 1280x720p at time)
(rpi3b+ installed in flirc case)

Code:

Time         ARM    Core    H264 Core Temp (Max)  IRQ/s     RX B/s     TX B/s
======== ======= ======= ======= =============== ====== ========== ==========
16:24:57  600Mhz  250Mhz  250Mhz 53.69C (54.77C)  4,075  1,028,008     68,378
16:24:59 1400Mhz  400Mhz  300Mhz 54.77C (54.77C)  3,864    822,087     55,828
16:25:01  600Mhz  250Mhz  250Mhz 53.69C (54.77C)  3,962    937,545     56,280
16:25:03  600Mhz  250Mhz  250Mhz 54.23C (54.77C)  3,951    946,925     58,735
16:25:05  600Mhz  250Mhz  250Mhz 53.69C (54.77C)  3,531    477,212     34,115
16:25:07 1400Mhz  400Mhz  300Mhz 54.77C (54.77C)  4,494  1,471,579     99,089
16:25:09  600Mhz  250Mhz  250Mhz 54.77C (54.77C)  3,060     21,716      1,663
16:25:11 1400Mhz  400Mhz  300Mhz 54.77C (54.77C)  4,541  1,499,581    103,033
16:25:13  600Mhz  250Mhz  250Mhz 53.69C (54.77C)  3,030        321        458
16:25:15 1400Mhz  400Mhz  300Mhz 54.77C (54.77C)  4,657  1,587,467    110,055
16:25:17  600Mhz  250Mhz  250Mhz 54.23C (54.77C)  3,035        112        395
16:25:19  600Mhz  250Mhz  250Mhz 54.77C (54.77C)  4,482  1,479,856     90,239
16:25:21 1400Mhz  400Mhz  300Mhz 54.23C (54.77C)  3,439    375,089     32,534
16:25:23 1400Mhz  400Mhz  300Mhz 54.23C (54.77C)  4,405  1,286,281     98,221
16:25:26 1400Mhz  400Mhz  300Mhz 54.23C (54.77C)  3,697    625,700     50,829
16:25:28  600Mhz  250Mhz  250Mhz 54.23C (54.77C)  3,941    904,732     62,642

Will tick off as RWT (Right When Tested)