Based on the zero responses, there’s no bootloader or it’s corrupted. Why there is pin activity with the led is hard to say, perhaps an incomplete flashing of the chip before installlation.
Why you where unable to install a bootloader is unknown. Connection issues would be the most obvious or something funky with your isp programmer. Eliminate the connections issues by installing the standard 6 pin isp connector in the open JP3 header and use an usbasp so you’re not messing with wire to wire connections every time you want to flash a board. Repurposing an Uno is inconsistent at best due to the header connections which are made worse by using round wires rather than square pins. Just spend the $5 for an eBay usbasp and a 10 pin to 6 pin adapter board. That way, flashing a bootloader is done with a constant ten seconds of effort.
If reflashing with a known good isp still fails, you’ve got a worst case scenario where either the fuses are wrong or the clock circuit isn’t oscillating, assuming there is no sign of processor activity. I’m unsure about that due to your earlier comments about a flashing led when the board is reset.
The only way to fix wrong fuses when there is no clock is to provide an external clock or use a HV isp programmer.