M50 swap first time cranking worked but now it won't crank

[sneakyRedPanda]

Using g260 flywheel trans and accompanying starter. Starter worked great first try turned over for about 10 seconds until I let go of the key. I had pulled my fuel pump fuse. Now it won't crank, starter solenoid clicks once each time I turn the key but nothing more. I figured my battery was dead after cranking it so much so I got it jumped and even with jumper cables and a measured 14+ volts over the battery terminals the starter still only clicks.

Suggestions?

[sneakyRedPanda]

New starter fixed it. Good luck anyone who manages to find this post in the future.