Why does my SF32LB52 board refuse to show up over USB?

Sounds like the USB port on that board is either power-only or the chip is sitting there blank waiting for a first flash. That LED lighting up tells you the 5V rail is fine, but it says nothing about the data lines. On a lot of these small square boards the USB-C connector is wired straight to the chip, and if the chip has never been flashed, or the factory firmware only runs serial on those TX and RX pads, your laptop will never see anything. No unknown device, no com port, exactly what you're describing. Before you give up on USB though, rule out the boring stuff. A shocking number of USB-C cables are charge-only with no data lines in them, so grab a cable you know transfers files with your phone. Also try a diferent port, and if your laptop only has USB-C, try through a hub or a different machine. One of those tiny buttons is ussually the boot button and the other is reset, but the timing matters. On boards like this the usual trick is holding boot, tapping reset while boot is held, then releasing boot before letting go of reset. Try that order with KEY1, then KEY2, and watch device manager the whole time. If none of that bites, the serial pads are honestly the normal path for a first flash on these anyway, not a worst case. You just need a cheap USB to serial adapter running at 3.3 volts, never 5, and you cross the lines, adapter TX to board RX and vice versa, plus ground. Then hold the boot button while powering it up and the chip should talk to the flash tool. The vendor has thier own download tool for this chip family, so check their docs for the exact pin order on those pads before you wire anything.

One day in and it's allready ignoring you, that tracks. Blank chips are stubborn like that.

I think suggesting that complicated button sequence is overthinking things, frankly. You keep telling people to worry about the precise timing of the reset and boot buttons, but if the USB data lines aren't connected right from the start, no amount of button juggling is going to make the chip appear. It feels like a bandaid on a bad wiring issue. If the chip is truly blank and hasn't been flashed yet, those buttons just won't help you establish a connection with the host computer. Unless the specific chip family requires that handshake sequence before it even exposes the basic serial functions, the primary problem is almost certainly the lack of functional data connectivity, not the command timing. Just verify the data lines are firing clean before you get obsessed with button combos.

Yeah I'm with the first reply that the serial pads are the normal way in, not a fallback. Had a similar little board last year that came totally blank, and USB did absolutely nothing untill I'd done the first flash over the pads. After that the port started showing up fine, so the hardware was never broken, it just had nothing to say yet. One thing that burned me: the TX and RX labels on the board are from the chip's point of view, so my adapter's TX actually went to the pad marked RX. Swapped them and the flash tool finally talked.

I'm only a few posts into this forum so apologies if this is obvious, but does the board have any silkscreen near those pads? My situation was similar with a different little board last month, and the tiny labels were so small I nearly wired the serial adapter backwards on my first try. I ended up taking a photo and zooming in just to read which pad was which. Wondering if yours has them marked at all or if you're guessing like I was.