The SD card slot is clean and its a small 4gb card so that should be fine. What do you mean by burn the image to the SD card? The guides seem to say that you need to just copy the extracted file to the card. I tried burning the image to the card using Rufus but I had an error of failed to scan image - I may just be being an idiot here.
It seems there is no .img file inside the tool it's a raw image firmware that works on old miners but the .img file for t9+ seems never exist.
Anyway, have you formatted the SD card to FAT32? Try to format it again and copy all files again to the root directory of your SD card.
If still doesn't work or it doesn't show any led signal when flashing check the jp4 if it's well attached.
Also, try another SD card, and maybe the SD card you currently use is broken which keeps files you copy corrupted/broken.
Once it's successful flash it again through the WebGUI use the 2017 firmware below this one is already deleted on their download page but the link still working.
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https://file.bitmain.com/shop-file-server/firmwares/Antminer%20T9%2B/Firmware/00720180209143644817e9j6NQuj06BF/Antminer-T9-PLUS-all-201711242319-autofreq-user-Update2UBI-NF.tar.gz