If you don't know the version of your backup, then you need to use this guide or this guide to restore your Switch. When you're done with the guide, you will have to update to 8.1.0 before it will boot normally (i.e. without fusee-primary or Hekate), assuming your fuses were burnt.
If your fuse count is low, then disregard the part about having to update. You will need to update to 8.1.0 if your intention is to use your sysNAND for online play.
Ten fuses means you did not preserve your fuses with AutoRCM properly. After following the guide, you will have to update to 8.1.0 for your Switch to boot normally.
If you ever once booted into 8.1.0 without AutoRCM, then that is what burnt your fuses.
You can use a custom boot.dat to launch Hekate with the SX dongle.
If you're using DZ Tinfoil, for example, you can install them the same way you install NSP files. Alternatively, you can convert XCI files into NSP files.
Is your new SD card exFAT? Is the old SD card FAT32? Does the Switch have exFAT support installed? Which error are you getting? Are you using an emuNAND?
