Based on advice from this forum, I dropped a 51R battery into my 08 Fit with no mods beyond a few cuts in the plastic battery mount. Unfortunately, the car won't turn over with the new battery. Has anyone else ran into issues installing a 51R? Did I miss some crucial step in the process?

Thanks for any advice.

 

A battery is a battery. Pulling one out and replacing with another shouldn't cause any issues.
1) Confirm that the battery cables are tightly attached to the correct posts on the battery.
2) Confirm that the negative cable still has a good attachment to the chassis ground.
3) Confirm that you got a good battery. It is unlikely that you would get a completely dead battery (e.g., you said the car doesn't turn over at all), but I suppose it's possible.
4) Confirm that all fuses are OK.