Reading the forum and experiencing pumping a PcP from dead empty air pressure can be impossible for some guns.
Try find some one close by and borrow his tank.
If all else fails even with cocking it and closing the lever shut and then putting on safe I cringe by mentioning this.
Some have mentioned they tried double loading 2 or 3 pellets keep it cocked then bolt or lever closed as if ready to shoot put on safe point towards a very safe direction then try to fill.
Probably want to remove the silencer first since it would likely get damaged after you try to shoot them through.
There is the real possibility the multi loaded pellets could shoot out with out warning as the air is being filled. Point it some where safe while airing up.
I would try several felt cleaning pellets instead for safety.
Yours is 30 caliber if you don't have cleaning pellets a local hard ware store find a couple of rubber 8mm plugs to load similar to like this or try different things safe to load. Can trim with razor blade if too tight.
https://www.ebay.com/itm/383807562173?hash=item595cb6a1bd:g:H2cAAOSwqARfrQIO Might be worth trying to plug the crown end stick the barrel end vertical point down in to your slipper to keep tight seal. Keep gun cocked and lever closed while filling.
Also buy a long round wooden stick alittle smaller diameter compare to 30 caliber pellet to un stuck it from the barrel crown end. Might not be able to shoot rubber bullets out.
Or take your chances with some pellets.
When you are like me have a hand pump and gun dumped all the air shot down after too low pressure you think any thing to get them to fill.
Or same thing when you receive it empty with out any air in it.
You really don't know if a dealer screwed you over and didn't check the gun for leaks before it got shipped and was full of air then leaked all out on its way to you.
I think shipping a gun empty degassed might be bad for the seals.
Could possibly leak like my Fortitude when I first received it degassed.
I was real ignorant not to request atleast have alittle air in it before shipping it.