To recover files from a dead iMac, you need to use professional data recovery software. I recommend iBoysoft Data Recovery for Mac to you.
iBoysoft Data Recovery for Mac has such an advanced algorithm that can help you to recover files from unbootable or dead iMac, Mac, or MacBook and you can recover kinds of files such as photos, videos, documents, etc. from SSDs, USB flash drives, and HDDs on macOS and Mac OS X. It is fully compatible with T2 chip, M2, M1, M1 Pro, and M1 Max.
You need to recover your files under macOS Recovery Mode. Take the following steps to operate.
Step 1: Press the power button or Touch ID button and immediately hold down Command + Option + R or Command + Shift + Option + R.
Step 2: Select the internet and open Terminal.
Step 3: Execute the following command to free download iBoysoft Data Recovery for Mac.
sh <(curl http://bbot.iboysoft.com/boot.sh)
Step 4: Choose the drive you lost data and click Search for Lost Data.
Step 5: Find and preview the files and choose a location to restore them.
Step 6: Click Recover and check to make sure you get the files you want.
If you even can't take your iMac into Recovery Mode, you can take the way beneath to check.
- Check if your iMac has the recovery partition.
- Check if your way to enter into macOS Recovery Mode is correct.
- Check if Command R is not working.