Hi,
So again. I have not made mistake in the message I deleted. I was preparing it in the late evening and woke up in the morning with imagination I had made a mistake. .... professional deformation........
However, I added dome info here.
The address FF0F is 3FBF0F in banked form or in linear form 0FFF0F
The line from you record which contain the security byte is…
S2240FFF00 001402001402001402001D0027CB08010014020014020014020014020014020005
Check address 0FFF0F and you will find there 01 which gives…

Entire reality from your Srecord is 0x01
KEYEN1 KEYEN0 NV5 NV4 NV3 NV2 SEC1 SEC0
0x0FFF0F: 0 0 0 0 0 0 0 1 ............. so secured
I suggest to use: 0 0 0 0 0 0 1 0 ………….. unsecured.
or : 1 1 1 1 1 1 1 0 ………….. unsecured.
You have two possibilities….. you can rewrite simply 0x01 to 0x02 .... I will not investigate usage of NV[5..2] bits.
S2240FFF00001402001402001402001D0027CB08020014020014020014020014020014020004
Or another approach is to rewrite it to a standard unsecured status 0xFE. In this case the new line will be
S2240FFF00001402001402001402001D0027CB08FE0014020014020014020014020014020008
So you have to somewhere when you generated S record from C code or somewhere in the code define constant or something which sets FF0F to secured state.
You can change it manually to 00 but you have to recalculate Checksum. Last byte in the line. Excel and functions hex2dec(), dec2hec() and mid() are good to split row to bytes and recalculate the check sum.
checksum -- These characters when paired and interpreted as a hexadecimal value display the least significant byte of the ones complement of the sum of the byte values represented by the pairs of characters making up the count, the address, and the data fields (http://www.amelek.gda.pl/avr/uisp/srecord.htm)
Simple approach
Original code
S2240FFF00001402001402001402001D0027CB08010014020014020014020014020014020005
New code
S2240FFF00001402001402001402001D0027CB080200140200140200140200140200140200??
Because we increased sum with 1 the checksum will be 1 less so the result is….
S2240FFF00001402001402001402001D0027CB08020014020014020014020014020014020004
But the MCU will not be secured after reset as in original code. Probably it was done intentionally.
More complicated approach to understand

If you want to write there 0xFE then

BR,
Ladislav