I've got some info on why bricks could be caused, I've got it working, and it seems nexo's system.xml is a little different from mine. Here's the two for comparison.
Here's mine, it doesn't brick upon sysNAND installation, successful coldboot.
Code:
<?xml version="1.0" encoding="utf-8"?>
<system type="complex" access="777">
<version type="unsignedInt" length="4">21</version>
<cmdFlags type="unsignedInt" length="4">0</cmdFlags>
<default_os_id type="hexBinary" length="8">000500101000400a</default_os_id>
<default_title_id type="hexBinary" length="8">0005000010179B00</default_title_id>
<log type="complex">
<enable type="unsignedInt" length="4">0</enable>
<max_size type="unsignedInt" length="4">8388607</max_size>
</log>
<standby type="complex">
<enable type="unsignedInt" length="4">0</enable></standby>
<ramdisk type="complex">
<cache_user_code type="unsignedInt" length="4">0</cache_user_code>
<max_file_size type="unsignedInt" length="4">10485760</max_file_size>
<cache_delay_ms type="unsignedInt" length="4">10000</cache_delay_ms>
</ramdisk>
<simulated_ppc_mem2_size type="hexBinary" length="4">00000000</simulated_ppc_mem2_size>
<dev_mode type="unsignedInt" length="4">0</dev_mode>
<prev_title_id type="hexBinary" length="8">0000000000000000</prev_title_id>
<prev_os_id type="hexBinary" length="8">0000000000000000</prev_os_id>
<default_app_type type="hexBinary" length="4">90000001</default_app_type>
<default_device_type type="string" length="16" />
<default_device_index type="unsignedInt" length="4">0</default_device_index>
<fast_relaunch_value type="unsignedInt" length="4">0</fast_relaunch_value>
<default_eco_title_id type="hexBinary" length="8">0005001010066000</default_eco_title_id>
</system>
Here's Nexo's, bricks upon sysNAND install, has more length=0 then mine.
Code:
<?xml version="1.0" encoding="utf-8"?>
<system type="complex" access="777">
<version type="unsignedInt" length="4">21</version>
<cmdFlags type="unsignedInt" length="4">0</cmdFlags>
<default_os_id type="hexBinary" length="8">000500101000400a</default_os_id>
<default_title_id type="hexBinary" length="8">0005000010179c00</default_title_id>
<log type="complex" length="0">
<enable type="unsignedInt" length="4">0</enable>
<max_size type="unsignedInt" length="4">8388607</max_size>
</log>
<standby type="complex" length="0">
<enable type="unsignedInt" length="4">1</enable></standby>
<ramdisk type="complex" length="0">
<cache_user_code type="unsignedInt" length="4">0</cache_user_code>
<max_file_size type="unsignedInt" length="4">10485760</max_file_size>
<cache_delay_ms type="unsignedInt" length="4">10000</cache_delay_ms>
</ramdisk>
<simulated_ppc_mem2_size type="hexBinary" length="4">00000000</simulated_ppc_mem2_size>
<dev_mode type="unsignedInt" length="4">0</dev_mode>
<prev_title_id type="hexBinary" length="8">0000000000000000</prev_title_id>
<prev_os_id type="hexBinary" length="8">0000000000000000</prev_os_id>
<default_app_type type="hexBinary" length="4">90000001</default_app_type>
<default_device_type type="string" length="16" />
<default_device_index type="unsignedInt" length="4">0</default_device_index>
<fast_relaunch_value type="unsignedInt" length="4">0</fast_relaunch_value>
<default_eco_title_id type="hexBinary" length="8">0005001010066000</default_eco_title_id>
</system>
--------------------- MERGED ---------------------------
Also, this is not fact, it doesn't even seem remotely related, everyone else who bricked had the game on usb/standby/quickstart enabled, that probably has a factor in the bricking.