If you can't get the systems to boot AND access the disk at the same time, you may have little reliable recourse other than to send it to a data recovery company. Gillware is frequently mentioned here as being cheap and reliable - and no charge if no success.
www.gillware.com.
One option - that frankly, I wouldn't expect to work, would be to put the drive in a freezer for 20 minutes and then try to boot it - I would be careful with this, if I remember correctly, I've heard this can also HARM the drive if it's left there too long.
Another option - that could be very tricky, find an identical drive and swap circuit boards. ABOVE ALL, DO NOT OPEN THE DRIVE. That can EASILY result in SEVERE data corruption - so much that even a data recovery service couldn't help.