Seeed has a new commit after v2.9.1 which solved battery reading but still got other issues.
The best way is to apply msfujino’s patch after upgrading to v2.9.1.
By the way I encountered a new problem today. The OLED of the expansion board which originally could display up to 8 rows of characters, failed to display the first 2 rows. It would only display on the 3rd row even though cursor was set to (0,0). This is very weird as the OLED had been working for a week. It started to behave like above after a power cycling. I noticed the OLED is a SSD1315 instead of SSD1306 after dismantling it off the board. While many users have no problems using 1306 library for 1315, I noticed a few of them got unexpected issues. I guess I am just another rare victim, sigh …