Seat the board first
The board fits into any base turned around as firmly as the right way round. Turned around, the base's 5 V pad meets the pin marked 3 and the battery rail drives three chip pins, so the check is one label at each end.
It fits both ways round
The two rows of holes on every base are the same footprint as the two rows on the C3 board, in the same order, so the board drops straight on. It drops on just as neatly the other way round.
Which pad meets which
The header is not symmetrical. One row is eight GPIOs; the other ends in 5 V, ground and 3.3 V. Rotate the board through 180° and those three land on the pins marked 3, 4 and 5 — so the battery rail goes into three chip inputs with nothing between them, and one of the three is half of the display's bus.
The rule printed on the box is antenna at the power-switch end, USB-C at the
battery-connector end. That is correct, and it is also a rule you have to
remember. The check that does not need remembering is to read one label on each
board: find V5 on the C3 board and 5V on the base, and make sure they are at
the same end. If they are, all sixteen are.
Do that with the switch off and the USB cable out.
When it does not work
Switch off and check the orientation before anything else. Turned around, the base's 5 V pad meets the pin marked 3, ground meets 4, and 3.3 V meets 5 — three chip pins driven from the battery rail. If that has happened the board usually does not come back, and there is nothing to repair.
Trust the labels. Find V5 on the C3 board and 5V on the base and put them at the same end; if they are, all sixteen pads meet the pad with their own name. The box rule says antenna at the power-switch end and USB-C at the battery-connector end, which is the same thing said in terms of parts.
Take the battery lead out and the USB cable out first, then look at the board. If it is warm or the screen never lights, it was turned around. If it is cool and merely dark, check that the base's switch is ON and that something is supplying power.
What the JST socket, the charger and the slide switch do, and why USB alone does not charge the cell.
The battery, the charger and the switch →Edit this page — content/books/c3oled/seat-the-board.mdx
Questions about this product
See what other owners have asked, and read their solutions.
This page covers several products. Choose yours to see the right discussions.
Discuss this article
Ask about this page. The answer stays here, on the page it belongs to, for whoever hits the same wall next.