Ble nano image max size using Arduino


I’m using the ble nano with the Arduino environment for a while now.
It great, but now I got to a size code of 58kbyte, the board stopped working.
I have the ble blinking led from the boot loader, then it goes on and nothing is running anymore.

I’m pretty sure my module has 256k flash, so why I can’t run code bigger than 58k ?