1. Take the files and figure out what to do with them so they can be read. This isn't a hard problem.
2. Ask everyone affected to email you the photo or a new photo of the documents. We'll just take it on trust that you do so honestly because there's no way you would've seen this coming.
That's not what happened at all. The college board admitted their fault and are letting students take the test again. Even without that, they mentioned in their FAQ that JPEGs and PNGs are the only file types acceptable and even sent out a tweet (which should have been an email) a week before especially for iPhone users to let them know how to take pictures as JPEGs.
I agree with the people blaming the board for not having a standard image input field that lets the OS know when to convert images to JPEG but that is their only fault and I wouldn't have thought of that as a bug deal if not for this issue. While I'm all for open source media formats replacing what we have, HEIC certainly isn't big enough to be considered as among standard input options. Also, isn't Apple themselves infamous for not supporting certain formats throughout their devices?
Communicating these issues only over twitter is also not at all acceptable. Plenty of people don't use or rarely use twitter, such that it should not be considered the primary communication channel.
So while yes, College Board is allowing students to retake the tests, anyone affected should be refunded at least partially, if not fully, for having their time wasted. College Board should have had their backend reject invalid formats, not just hang. The result of attempting to upload an invalid format image should have been a 'whoops, please use a different format', but that's not what happened.