transmission swap no start no crank

[paleface]

Hello. Just completed a 4r70w swap into a 2004 mustang gt. However now it will not start nor crank. It did at first, the starter would spin but not engage flywheel. But after tapping the starter that stopped and as soon as you turn the key to start the dash lights and gauges return to 0 or off and it will not start. Starter is good, we jumped the starter and it cranked but didn’t turn on so not the starter as its also brand new. Checked all fuses and found starter relay fuse was blown. Checked driver compartment fuses and all voltage across all fuses were normal. neutral safety switch is also good. Any tips? stuck in Theft? PCM? Need help asap