Hi!

Yes, the M5Stack Battery Module works with the M5Stack Fire 2.7. M5Stack's stackable header-pin design allows you to simply add modules like this one without needing to solder.

Use M2 screws (22mm or longer) and M2 brass spacers to securely assemble everything. This maintains the modules securely packed, which is ideal for preventing inadvertent disassembly, particularly in client-facing installations.

If you are in India, check out Robocraze. They are an approved M5Stack distributor, providing accessories and assistance for clean, professional builds.

Hope this helps!

For improved performance, use a Raspberry Pi 4 (4GB), which Robocraze sells. They are the authorized seller of Raspberry Pi Boards in India. For the last two months, I have been using this configuration without any problems. Conflicts over power or networks may be the source of your issue. Have you looked into if the M5Stack Unit V2 is using the USB excessively? Consider using a separate power source for the M5Stack or a powered USB hub.