Ok guys, so I found a forum for the same problem but with the Neptune Elite keyboard instead, however in that case, a PM came by and dropped a link to a file to fix the update.
Here's the link: https://drive.google.com/open?id=1voGuwm1daSZvXEc6wa8_lfnrxovsjXeQ
Here's the full reply
"Good day, I’m Thermaltake PM, Stephen. I understand that there’s been an error during the FW update on your Iris MIKU Edition mouse.
Please update the mouse again via the FW updater file, link below. If any question, please let me know.
Thank you for your patient and understanding. We apologize for the inconvenience
TEL: +886-2-87975788 #2856