Hey y'all I hope this is the right place for what I need.

I have a 1995 lexus sc400.
I recently swapped a newer 1uz from another
95 sc drove it for a while and everithing was ok.
I go to drive it again but the tranny decides to stay in first gear no matter what i do.
speedo isn't working o/d light is blinking all the gears are still the same and they work good r,n,p there are no ugly noises coming from the tranny.

What could be the issue ?