a. Please check the log via a USB to Serial cable.
b. Try to update the firmware according to this guide link.
Q2: Can I flash the firmware via a USB drive.
A2: Here is the instruction file.
a. Save the firmware file (lks7688.img) to the root directory of a USB drive.
b. Plug the USB drive to the development board.
c. Press the Wi-Fi and MPU (Reset) buttons, then release the MPU Reset button only while holding the Wi-Fi button for at least 5 seconds and release when the Wi-Fi LED turns off, see below for detailed LED status. Do not press the Wi-Fi button for longer than 20s or the development board will enter boot loader mode and erase all user data.
Flash firmware LED Status
Q3: What is the power consumption of the LinkIt Smart 7688 development boards?
A3: Please refer to Section 2.2.6 "USB Power"of the LinkIt Smart 7688 Developer’s Guide for detailed power consumption information.