Figures for 3040 :
ThinOS 8.6 booting time : 25 Seconds. Dell logo at screen.
ThinOS 9.1 Booting time : 51 seconds (!). In fact the worst part is a 26 Seconds w/ a totally black screen.
Given the fact the the power led is white and not exactly bright (was bright blue on 5010 / D10D), the power status maybe hard hard to figure out for sure. So, you press again…shutting the damn thing down.
(BTW, our 20 first 5070s (from late 2018) power LED are defect. They are very very dimmed from the beginning. After sending an item in Asia for analysis, they admitted the problem and provided new LEDs )