Okay. So this is a rebadged Liteon, LG or Samsung drive. The good thing: this unit is covered by warranty (normally at least).
My computer crashed about a week ago and I've had to reinstall Win XP SP3 and all the rest of my software.
Did you use this drive for reinstallation?
My firmware installation CD won't work because it's become unreadable.
Delivering a firmware update on CD with a new drive is, cough strange. So I doubt you have a firmware installation CD.
A bad disc can happen, though. Nothing to blame the drive.
Windows PnP will only recognize the device as a CD writer.
What does Device Manager report? How is the drive displayed in "my Computer" exactly? Drive without disc inserted and system fresh rebooted.
Windows XP has no support for DVD writing, and that a DVD drive is often displayed as CD drive is a bug ^W feature of Windows XP explorer.
Memorex's online support does not even list this device as one of their products (although it's clearly still out on the market... so there's no firmware download for it.
There is no firmware related issue.
Try the drive with another computer. If there is the same problem, then contact the vendor and have it fixed under warranty.
I tried to download the firmware for a discontinued 20x burner ,
since, aside from the max burn speed designation, it's identical to the 24x
What made you sure this assumption was correct?
(and also because I had no other choice).
Wrong firmware is never a choice. Apart from that, your problems are most likely not firmware related at all.
The install failed, with an error message that said there was no device attached and that the firmware was only for that specific device.
Flashing the wrong firmware is an excellent method to kill a drive. Perhaps drowning in the toilet or treating with a hammer is more fun. You can really be glad that there was some compatibility check in the firmware update utility.
Any help/suggestions would be greatly appreciated. This thing is too bulky to use as a coaster/paper weight and too small to pass as furniture. I am so totally at my wit's end.
As already mentioned: Try with another computer. Additionally you can try on your own system running Linux from a Live CD (Ubuntu for example). If the problems are present there, also, then it's time to RMA.