Replacing USB-A with USB-C fails
I don’t understand what went wrong.


What went wrong is that you cut a wrong type of Type-C cable. From your imprecise description you took a part of Type-C to Type-A PLUG cable. This kind of cables are designed to connect a USB Type-A HOST to Type-C device. So essentially the cable must fake the USB host signature. It is doing so by having PULL_UP resistor on CC line to VBUS, typically 56k.

Yours is a device, so the captive Type-C end must have "device" signature, which is 5.1k PULL DOWN on CC pin. To make it work you need to get an 
OTG adapter, Type-C to Type-A RECEPTACLE, like this one,



and do the same soldering work. Before cutting and soldering, make sure that the adapter works with the phone (use a pen drive or mouse), some adapters don't have proper pull-downs and don't work.