I'm facing the same problem as you. I've followed the same steps as you and nothing seems to work.
I changed my freestyle libre 1 sensor last sunday and when I connected the Miao Miao 3 sensors it kept saying that no sensors were connected. When I try to reset it (by plugging in the charging cable), it has connected to the Suggah app and sent readings. But when the cable is disconnected, it stops working immediately.
So I tried to update the firmware, but now my Miao Miao started flashing red light and now nothing seems to work anymore.