2. Attack the blockchain itself. It can stand bozo-scale hacks, but NSA scale? They control the internet backbone. They can just drop the packets. They have hardware backdoors all over the place and have been known to successfully hack completely airgapped setups. Maybe they even bring clever math/chips to the fight. That's more speculative than necessary, but again, not actually very speculative next to their historical accomplishments.
3. Deploy police to server room. Or special ops, if they played the non-extradition-country game correctly.
We aren't talking about Goldfinger levels of infrastructure. No secret island nuclear program is necessary... but even if it were, remember that superpowers are absolutely capable of that sort of thing.