Restore MTD backup

I've made a backup with the following script:

Now I kinda messed up with sysupgrade, had to reflash my stock firmware and wanna get back to the old openwrt I had on with all the packages and configs.

But there is no real guide on how to restore that backup? I tried restoring overlayfs via dd but the packages are still missing. Plus it rebooted straight after without asking. So copying them over one at a time would probably take a lot of time. Is there any recommended way to revert back to the backup from my current running openwrt build via ssh?

My MTD layout:

cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00100000 00020000 "0:sbl1"
mtd1: 00100000 00020000 "0:mibib"
mtd2: 00300000 00020000 "0:qsee"
mtd3: 00080000 00020000 "0:devcfg"
mtd4: 00080000 00020000 "0:rpm"
mtd5: 00080000 00020000 "0:cdt"
mtd6: 00080000 00020000 "0:appsblenv"
mtd7: 00100000 00020000 "0:appsbl"
mtd8: 00080000 00020000 "0:art"
mtd9: 00080000 00020000 "bdata"
mtd10: 00080000 00020000 "crash"
mtd11: 00080000 00020000 "crash_syslog"
mtd12: 023c0000 00020000 "rootfs"
mtd13: 023c0000 00020000 "rootfs_1"
mtd14: 01ec0000 00020000 "overlay"
mtd15: 00080000 00020000 "rsvd0"