Precision 3530, error code 2000-0155, 2000-0620

Feel free to refer to this article to reference the error codes that were received. In short, the 0155 code indicates the hard drive is not detected and the 0620 code is finding an issue with the NIC port/adapter. I've normally found the 0620 error to be a false positive, but check for any damaged pins on the port first. If not damaged, then does your wired network connection work? If so, then it can probably be disregarded. If it does not, but you have a connection with wifi, then download the latest BIOS and network drivers to try and resolve the issue.

With the 0155 error, first perform a hard reset by disconnecting the battery, holding the power button down for 10 seconds, then reconnecting power. If unresolved, reseat the SSD. Depending on how your model was configured at the time of purchase, you can try testing the SSD in the WWAN slot if still not detected. If the SSD does not work in either slot, try a known good drive if available. Loading the BIOS defaults is another viable step. If a known good SSD fails to be detected, then it's likely a bad slot requiring a motherboard replacement.