Hi there, Ben!
Will work. IDE or scsi?
Read the readme of WinUAE on how to have the PC surely recognise the disk. (there is a checkbox that forces UAE to recognise HD's that initially fail to, so don't be dissapointed if it isn't recognised at first.
About the miggy, have you tried a different monitor?
Is the flashing of HDD like reading (booting) or it flashes shortly twice then dead?
Check for odd resolutions improperly loaded
using the two miggy mouse puttons pressed continously while swiching on the amiga and for at least 10 seconds,
to call early startup to see if it does anything. then boot with no startup-sequence if it does and load a backup of your startup-sequence and user-startup if it does.
which monitor are you using? Is it a PAL monitor or a VGA via the FlickerFixer?
A moderate shock could loose the CPU board, if installed.
Power disconnected, all cables too. open the cover, remove the HDD cable and push all chips that are base-mounted deep in place to ensure all chips haven't loose contacts due to vibration or mechanical shock. Do that with any boards, too. Cover back on,all cables attached but the HDD flat cable, try to swich on the amiga and watch the monitor for "insert disk" screen. If it shows, power off and put HDD Flat Cable back in place, then on.
A shock could have moved the