It's possible your PC motherboard is blocking the locking signals. If you've used it for this sort of thing before, then that won't be the case, but if you haven't then you could try disabling the automatic IDE detection settings within the CMOS setup screens.
Either way, flashing is probably your best bet.
The save game exploit is just one way to boot a flashing tool. You can also use something like the EurAsia Flash Disc, and I'm pretty sure stuff like Auto Installer Deluxe provides flash tools as well.
There are a few choices available to you as far as the BIOS goes (the v1.0 consoles have a 1mb TSOP chip). I use the X2 5035 myself. Make sure whatever version of whatever BIOS you use is compatible with your console - some are specifically intended for certain machines (eg, there's a 1.6 release of the X2 5035, and an "old" release for all consoles prior to the 1.6).