You mention you have ‘Updated’ the SSD and the motherboard - do you mean you have updated the SSD’s firmware, and the motherboard’s BIOS/UEFI?[br]
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Regardless, the first thing I would try, rather than checking connections, would be to actually ''disconnect'' the boot drive - ''and'' all other drives, ''and'' all other USB peripherals; you just want the PC on its own, with nothing connected. [br]
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If you can then get the machine to consistently boot through POST, and arrive (as it should) at a black screen saying it can’t find a boot device, it could well be a faulty drive. I’ve seen many faulty drives behave inconsistently like this - sometimes they’ll boot, other times they won’t. If it’ll do this five times in a row, you’ve found the culprit. If it still acts the same, at least you’ve ruled out the SSD, and it’s more likely to be the motherboard itself. [br]
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In that case, have you tried going into the BIOS/UEFI, and resetting everything to default?[br]
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If it behaves well without the boot drive in, and you have another PC, you could also try connecting the boot drive to it using a USB adaptor, and doing a CHKDSK /r on all partitions. It’s unlikely this is the problem, but a corrupted UEFI partition might cause similar symptoms.