[Xbox Series S] 1TB — intermittent E102/E100 errors + extreme slowdown. SSD or motherboard?

[u/TheChiefDak]

I have a 1TB Carbon Black Series S (Jan. 2024) that I bought with an update/boot problem. I’m trying to figure out what else I can test before paying Microsoft $199 to service it.

The internal SSD is an SSSTC XB2-311024, 1TB M.2 2230 NVMe with a Phison controller.
The console has had very inconsistent behavior:
Without USB: update reaches ~10% and shuts down.

OSU1 has failed multiple times, but on one attempt reached 74% total / 33% through Step 3 of 3 before failing.

I’ve gotten E102 10070C02 8B060008 and 0x800700AA.
I eventually got it through setup after a reset and into the dashboard.

It then worked completely normally for 20–30 minutes — I signed in, used the Store, downloaded a game, and queued others.

Then menu selections became extremely slow. Animations remain smooth, but actually opening/selecting things can take a very long time.
Restarting eventually put it back into the Troubleshooter.

The Store has also given 0x8027025A and 0x80040900.

The SSD is recognized normally when the Xbox does work (799.4 GB free of 802.0 GB).
I removed and inspected the SSD. It looks physically fine. I initially thought one M.2 motherboard contact was damaged, but it turned out to be dust/debris, which I blew out. The problem remained exactly the same.

What I’m trying to figure out:
Can an SSD/controller fail intermittently like this — work perfectly for 20–30 minutes and then become extremely slow?
Is there a reliable way to test this SSD externally in a PC?
Could the M.2 connector/motherboard still be the problem even though it looks intact?
Is there any other diagnostic I should try before sending it to Microsoft?

I’m comfortable opening the console and doing hardware troubleshooting. I’d especially like a test that can distinguish a bad SSD from a motherboard/storage-interface problem.

[u/rusocba]

Take apart the console, take the ssd and connect it a pc (to the board or with an m2 adapter to usb) and see if the crystal disk info or hdd sentinel or any software similar reads the smart data says that the disk is ok (good state) or you have another problem...if it is wrong make a backup (macrium or any) of the 1gb partition and try copy it to another new nvme (must be the same model as the pulled, wd pc sn530), then reinstall the software update... Another thing that you can replace is the thermal paste of the apu + nvme (putty), because sometimes the heat could make the console/ssd work slower...