Hi Mircea Udrea,
Thank you for your interest in NXP Semiconductor products and the opportunity to serve you.
Please refer to the attachment to assure the MCU enter the ISP mode successful via properly hardware configuration.
And I'd like to suggest another way to 'release' the LPC54608.
First, you should update the on-board LPC-Link2 with the JLink firmware,
then follow the Fig1 to work it out.
Fig 1
Have a great day,
TIC
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