I've not heard of any DSi firmware v.1.4J. Typo? Care to fix with correct info?! But as far as I know, the R4i Dual Core 2013 (if assuming it's from the R4i SDHC team as there could be more than 1 R4 cart brand going by that name), it should work on the latest DSi firmware. On condition you'd pre-upgraded the flash cartridge's firmware prior to upgrading the DSi's firmware. Else it's blocked (especially if the screen when cart is loaded gives an error message). On the other hand, if the flash cartridge is in the cart slot, but the DSi went straight to the system menu without giving any error info; then it's either the cart is dead or the DSi's cart slot is damaged. So yeah... that's about all I can say with such minimum information you'd given.
my R4 Dual Core White 2013 is from R4i SDHC My dsi xl is a Japan version thats why its 1.4J My R4 dualcore white 2013 works fine on my 3ds 7.0-14U
I'm quite sure it should have said 'v. 1.4.5-J' instead of just '1.4J'. In any case, if it runs on 3DS v.7.0-14U which needless to say means you'd upgraded the cart to run on the latest 3DS firmware. It should have loaded on the DSi's firmware no matter what version firmware it's running. So I should suggest you try loading other cart into the DSi's slot and see if it reads it. If it doesn't then it is obvious that the problem lies in the console's cartridge slot. In which case, you'll have to send it for fixing.
