I'll try an explain this so slowly, even you can understand.
Your 1st paragraph. the image is an exact copy of everything in the server at the moment it was imaged. Yes, it probably could be. It could also be an image, faked, time stamped to look legit.
The FBI needs the device to verify that the image provided is indeed a legit copy, by using tools to compare the hardware memory , logs, versus the image.
Yes, the FBI does have the capability, has does most of the govt secure facilities.
do I think a computer security company has the talent to pull this off? If they don't, then the DNC is an absolute fool for hiring them.
Granted, your party also hired Imran Awan. A paki who fled the country, and likely also stole state secrets.
https://www.politico.com/story/2017/08/10/debbie-wasserman-schultz-scandal-241466
Lastly, you ignorant dumb jackass, do you think when the FBI kicks down your door, for fraud, they let you provide the image of your laptop?
Not a chance in hell.
Only if you're Hillary or the DNC.