First, check the power pin voltages.
Then try connecting to the internal bootloader, ie via uart. Pull the boot0,1 pins to bootloader mode, connect uart to pc and launch the software. If it connects, the problem is in jtag side.
The st-link is cheap enough, that you can get the real thing. Check the connections - for connecting up, you need SWDIO, SWCLK, VCC, GND. Usually you need RST too, but having RST not connected would not cause swd connection failures for empty chips (there may be issues when the fw has put the chip in sleep).