Black screen with caps lock blinking.

If you do not care about the laptop, the drives on these are easy to pull. What you need to do is remove the hard drive door (Hint: It’s the wide cover to the left or right of the RAM door, which is in the center). Once you remove the drive, pull off the interposer and put it in the laptop for safe keeping just in case you repair it. Get a good USB>SATA bridge, and copy off the data. You will need something like this to pull it off.

As far as repair, that code usually points to loose or failed RAM, or a faulty RAM socket. Usually, it tends to be due to one bad RAM module in many cases with dual SODIMM HP laptops rather then a bad slot. These use DDR2 RAM so it may not be cheap to get a new matched pair so consider that carefully as well. That said, if you have 2 modules from the factory you can remove both and only run one at a time and see if one of them has failed. If both work, try them in the other slot to rule out a possible slot failure. If it has 4GB, then buy a set of 2x 2GB DDR2 sticks at the bare minimum to bring it back where it was. However, bear in mind HP has pulled the drivers for it so even if you fixed it then you’re going to need to hunt for them if the drive ever had to be replaced.