brief explanation of Ohm's law
Assuming that ideal short has a resistance of \$ 0 \$ ohms (so infinite conductance \$ G_{open}=\infty \$) and ideal open circuit has infinite resistance (so zero conductance \$ G_{short}=0 \$) and voltage of ideal source is greater than 0:

$$
I_{short} = G_{short} \cdot U = \infty \cdot U = \infty A
$$
$$
I_{open} = G_{open} \cdot U = 0 \cdot U = 0 A
$$

Look for this simple circuit with two batteries with different voltages, connected in parallel with ideal zero ohm wires, so they have infinite conductance. We assume that battery is an ideal voltage source, without internal resistance.







simulate this circuit &ndash; Schematic created using CircuitLab

Potential of node V1 is 2V and potential of node V2 is 4V, so voltage between V1 and V2 is:
$$
U_{V1,V2} = U_{V2} - U_{V1} = 4 - 2 = 2V
$$
and then the current flowing through the ideal wire is:
$$
I_{wire} = U_{V1,V2} \cdot G_{wire} = 2 \cdot \infty = \infty A
$$

Of course, for above example we assume that every element in a circuit is ideal. In real circuits they are not, batteries has internal resistance from hundreds of ohms (for small button cells) to several ohms (for big car batteries), wires and connections has resistance of miliohms to ohms. So short current never be infinite, but may be very huge and destroy elements thermally.