trim/tilt manual release issue

[Taurus2T]

I have a 1998 135 Mercury outboard. The trim/ tilt motor went on it last season and figured I'd replace it beginning this season. I stored the boat outside with engine in full down position. So today I start to get to work and the outboard is locked in place. I open manual release valve all the way and still will not budge. Could I be missing something? Thank you,

 

[galamb]

......

Sorry, was initially thinking might have reverse lock, but shouldn't be present with power trim/tilt.