stm32f030cct6 SWDIO is pulldown when i try to program and my STLINK can't find the tarjet

[Frisopita]

I am trying to program a stm32f030cct6 with a ST-Link v2. When I try to connect using CubeProgramer  says: "Tarjet not found". I connect to NREST, CLK and SWDIO, I'm measuring the signals with an oscilloscope and SWDIO is in PullDown when it should be in PullUp, as it says in the datasheet. Note that the clock takes some more time to start toggle, about 200 ms.
I don't know what could be the error

Thanks.

[ONadr.1]

Try to connect NRST via the button to GND. Press the button and then start "Connect" and release the button after about a second. Then it is best to do a "Mass Erase".

[Frisopita]

Thanks for your Answer. Do you think that the microcontroller is blocked? and how this method can help me to solve it?