Got any pictures of your input (trichomes) or output (rosin)?
To get your extract into the cart, it needs to be less viscous. Just heating and loading MIGHT work.
I’ve been known to refill a cart with whatever was on deck using a dab tool and a torch… it works better if you decarb first, but will work without in the right hardware. A quick “preheat” with a torch can be useful for stubborn/stable extracts.
Some folks like to separate the “terps” from the cannabinoids before decarb. To protect the terpenes from the deliberate heat degradation being applied to the cannabinoids. Some don’t bother.
An inert atmosphere may help.
A pressurized vessel can be used if you can’t be bothered sepArating your cannabinoids from your “terps” pre decarb.