Welcome to the forum. Its a great place here

Don't beat yourself up too much about your mistake. The good thing is you have realized it was a mistake, and now we just have to focus on building up her trust in you and confidence in flying again.
Don't cut her wings again. I'm not sure what you'll be able to do if she begins crashing again - the only thing i can suggest is to reward her for flying at a comfortable level, and flying to certain targets around the home - so you have a, b and c perches etc..., reward her with scritches or attention or nuts, etc...when she flys to and lands successfully on the designated perch. If she doesn't, simply don't reward her. Now - this might not help stop her from crashing into things, but she will more likely be motivated to fly to one of the targeted areas in a sensible way to get the reward, over time, you can slowly minimize her rewards until its so engrained that she'll do it automatically.
Shes probably not motivated to come out of the cage because her wings were cut and shes lost some trust in you, and herself.
Start things over with her again. Just the simple things, if she doesn't want to come out of her cage, let her step up on your hand in the cage - if she doesn't want to, don't make her do it, just close the cage and walk away - she learns two things from this - that your not going to force her into doing something she doesn't want to do - you respect her wishes, and she is left alone if she doesn't interact with you. When she does make the decision to get on her hand, you can give her a treat, but don't take her out of the cage unless she's walking up your arm. Do this a couple of times, and maybe after a while you can take her out of the cage doors - but make sure she can get back to her cage with ease - you could rest your hand on the door so she has the option to go back in.
If you have a smart phone, you could probably download an application that will make the sound for you, that way its constantly the same noise.
Target training, and then target flying training will be a fantastic thing for sonny to help build up her confidence in flying again, and help get the strength back in her wings

good luck