It is fairly easy for the state to file criminal charges, because it only needs something called probable cause to do so. Probable cause is just a reasonable belief that you may have committed a crime, and as you can see, that doesn't take much evidence. Here, the machine was working. You had been the last known person in the room. Then it was broken. Arguably, that would give the state a reasonable belief that you were the one who had to have broken the machine.
However, in order to convict you, the state has to do a lot better than that. They have to prove the case against you beyond a reasonable doubt. What they have is what's known as a circumstantial case. That is, there don't appear to be any witnesses who saw or heard you damage the machinery. They appear to be basing your guilt on the fact that you were the last known person to be in there.
So if you wish to retain counsel and fight the charges all the way to trial, the state would have to try to convince a jury that there is no other possibilty tha anyone else could have broken the machine. I don't know what evidence they will martial to meet their burden of proof and whether it will be good enough. As the case goes on, your lawyer will be able to get discovery and he can get an idea of that and inform you.
If you didn't want to risk trial and a possible prison sentence, your lawyer could likely get you a plea bargain involving probation and restitution. That is, you'd be able to remain at liberty and part of your sentence would be to pay off the damage done to the hospital's equipment. Typically, a non-incarceratory offer can be negotiated for a first non-violent felony matter.
I'm not sure what else you want to know, so if this does not address all you were looking for, please reply on this question thread and tell me so that I can amend my answer.