dsi bios7.bin alone is insufficient. Unlike the original DS, the DSi also requires a (a copy of the console's internal flash memory) and a firmware file . The ARM7 BIOS is just the bootloader; the operating system lives in the NAND. Without the correct dsi_nand.bin , the ARM7 will spin in an infinite reset loop.
Commands (examples):
Here are the standard files needed for full DSi emulation: dsi bios7.bin
What (Windows, macOS, Android) are you running? dsi bios7