The Li-Ion battery holder is visible on one side, along with the USB Micro-B connector that in this case has been damaged.

USB Connector is a Wurth Electronics part #629105136821

Battery is a LIR2450 3.6V 120mAh rechargeable Lithium-Ion button cell.

The other side of the PCB shows the main components including:

CC2640: Texas instruments wireless MCU with Bluetooth

MX25L3233FM2I-08G: Macronix 32Mbit Serial Flash

MPU-6500: InvenSense 6-Axis motion tracker (3-Axis Gyroscope and 3-Axis Accelerometer)