Help on unprogrammable Kinetis,pulse on RST pin

Hello
please, can i have some help?

For a reason that i still don't know i have that my Kinetis MKL15Z128 is 
impossible to program or debug.

It is mounted on an almost-empty board,where i have the uC,with connected 
and decoupled supplies and GNDs.
The programming was done via the SWD interface, SWDIO,SWDCLK,and RST.
No crystal oscillator is mounted

I have a pulse on the RST pin,36KHz,2us H width,24us L width;
the referencd manual states:
"For all reset sources except a VLLS Wakeup that does not occur via the 
RESET pin, the
RESET pin is driven low by the MCU for at least 128 bus clock cycles and 
until flash
initialization has completed.".
I think this is my case,correct?

A Freedom Board FRDM-KL25Z is used as a programmer to the external target 
MKL15Z128,
I can see that its RST is not strong enough to prevail on the pulses coming 
from uC,and any attempt to write or erase the Flash memory fails.
How to get out from this situation??
Thanks for your attention

Diego,
Milan,Italy