There are 5 buttons on the front panel, as shown in Figure 7, that work as Power, Brightness+, Brightness-, Audio output Volume+, Volume-.
The product CS19108RA4156A supports 2 boot modes, auto boot, and manual boot. The default boot mode is auto boot mode. The boot mode can be changed by using Software or by pushing Volume+ and Volume- buttons at the same time before power on, and releasing it 3 seconds after power on to toggle, as Table 1 shows.
The product CS19108RA4156A boots from the internal eMMC by default. If you want it to boot from the Type-C connector, you need to push the Volume+ button BEFORE power on, and release it 3 seconds after power on.
You can use Brightness+ / Brightness- to control the backlight of the LCD.
You can also use Volume+ / Volume- to control the System Volume.
For a detailed explanation of button functions, check Table 2.
Table 2: Button Functions