So what happened is that I actually had to choose between UCSD and UCI; however, after a while, I started to reflect on my own reason on choosing UCI. For me, I thought over it and I found that my decision (I SIR to UCI btw) felt incorrect. I now wanted to see if I can possibly go to UCSD even though I had just SIR to UCI. I know it is a bit late but I want to see if there was any hope in making any possible changes.
I would call UCSD and ask if there’s any way you can accept their offer or if they have any space left for you. If FA is also a factor, just know that it is unlikely they will be able to award you your original FA award.
If they say yes, and you deposit, you should then call/email UCI, apologize, and tell them your plans have changed, and that you won’t be attending this fall. You will almost definitely lose your deposit, so just be aware.
Are you transfer applicant? It seems a little late for freshman year.
Why don’t you check with them directly instead of asking here?