Trying to convert Binary to Decimal to Hexadecimal in Python without inbuilt Functions

Question

So I'm trying to use Python to convert a Binary number to a Decimal number to a Hexadecimal number.

I need to use functions for this, but not the inbuilt ones. Specifically, I want to use a binToDec (binary to decimal) function, a decToHex (decimal to hexadecimal function), and lastly the main function where all the code will run. Below is what I have done thus far, and it has several errors, but my brain is spent on this and I was hoping to get some collaborative help. Thanks!

Edit: The errors are with returning hex_value and calling hex_num

def binToDec (binary):
    count = 1
    dnum=0
    while(binary != 0):
        rem = binary % 10
        dnum = dnum + (rem * count)
        count = count * 2
        binary = int(binary / 10)
    return binary

def decToHex (dnum):
    while (dnum > 0):
        hex_value = dnum % 16
        dnum = dnum // 16
        if (dnum < 10):
            return str(hex_value)
        elif (dnum == 10):
            return "A"
        elif (dnum == 11):
            return "B"
        elif (dnum == 12):
            return "C"
        elif (dnum == 13):
            return "D"
        elif (dnum == 14):
            return "E"
        elif (dnum == 15):
            return "F"
    return hex_value

def main():
    binary = int(input("Please enter a binary number: "))
    dec_num = binToDec(binary)
    hex_num = decToHex(dec_num)
    print("You entered the hexadecimal number: " + str(hex_num))

main()