9_Hardware Modifications Needed

The board we brought from Taobao, although is well packed, does have some design flaws, if you encounter the following issues, try the suggested way to solve them.

1. The BOOT0 switch sometimes loss contact during programming, causing wrong or unstable binary uploading, this is resolved by soldering a wire shorting the BOOT0 pin to ground.
2. The pull-up resistor on the I2C2 bus were too weak at 10k ohm, replace those resistor (R6,R7) with smaller values (<4.7k). This may require some soldering skills to accomplish.